I stopped wondering years ago about who is enlightened because I think it is always motivated by tanha. What we can know about a teacher - beyond speculation- is whether they point to the present moment in a way that helps us to begin to insight such moments. The rest is wishful thinking.
The Anguttara nikaya commentary tells the story of one teacher, after the Buddha’s time, who had many pupils all of whom attained arahatship.
. But he was still a wordling - not even a sotapanna. However, he understood the tipitaka very, very well; knew the letter and the meaning and so was a great teacher.
see (Angutara nikaya Ekakanipata pali (the book of the ones) Nivaranapphahana-vagga (abandoning of hindrances) 6th sutta; about the Thera Gamantapabbharavasi mahasivatthera ). Many of his students became arahant[not entirely sure of this number I can`t find the orginal pali at the moment]
Later he himself attained.
here is a link to an account:
Mahashiva, Mahāśiva, Maha-shiva, Mahāsīva: 7 definitions (wisdomlib.org)
Scroll down and you will see his name.
Mahasiva Thera. Resident of Vamantapabbhara. He was among the last of the arahants, and had taken part in various assemblies led by the Bodhisatta (J.iv.490; vi. 30). It is probably this Thera who is referred to as Gamantapabbharavasi Mahasiva in the Anguttara Commentary (AA.i.24, 29). He lived in Tissamaharama at Mahagama, and was the teacher of eighteen groups of monks. One of his pupils became an arahant, and, being aware that his teacher was yet a puthujjana, went to him and asked his leave to be taught a stanza. But Mahasiva said his pupils were so numerous that he had no time to give him a stanza. The pupil waited for a whole day and night, and then getting no chance of learning, said, If you are so busy now how will you find time to die? Mahasiva heard and understood, and exerted himself strenuously for thirty long years, at the end of which time he became an arahant.
The commentaries explain that examples like this where a puthujjana teacher helps his students to become ariya is like the Buddha was their teacher (because the putthujana teacher is using the Buddha’s words).
This is true. We need not to be so attached to find enlightened person to teach us. Instead, we have Dhamma and Vinaya here acting as our Teacher.
Here is some of the context
ekaccassa pana vuttanayeneva dhutaṅgāni pariharato kileso okāsaṃ na labhati, dhutaṅgavasena vikkhambhitova hoti. so taṃ tathā vikkhambhitameva katvā vivaṭṭetvā arahattaṃ gaṇhāti gāmantapabbhāravāsī mahāsīvatthero viya. thero kira mahāgāme tissamahāvihāre vasanto tepiṭakaṃ atthavasena ca pāḷivasena ca aṭṭhārasa mahāgaṇe vāceti. therassa ovāde ṭhatvā saṭṭhisahassa bhikkhū arahattaṃ pāpuṇiṃsu. tesu eko bhikkhu attanā paṭividdhadhammaṃ ārabbha uppannasomanasso cintesi – "atthi nu kho idaṃ sukhaṃ amhākaṃ ācariyassā"ti. so āvajjento therassa puthujjanabhāvaṃ ñatvā "ekenupāyena therassa saṃvegaṃ uppādessāmī"ti attano vasanaṭṭhānato therassa santikaṃ gantvā vanditvā vattaṃ dassetvā nisīdi. atha naṃ thero "kiṃ āgatosi, āvuso, piṇḍapātikā"ti āha. "sace me okāsaṃ karissatha, ekaṃ dhammapadaṃ gaṇhissāmī"ti āgatosmi, bhanteti. bahū, āvuso, gaṇhanti, tuyhaṃ okāso na bhavissatīti. so sabbesu rattidivasabhāgesu okāsaṃ alabhanto, "bhante, evaṃ okāse asati maraṇassa kathaṃ okāsaṃ labhissathā"ti āha. tadā thero cintesi – "nāyaṃ uddesatthāya āgato, mayhaṃ panesa saṃvegajananatthāya āgato"ti. sopi thero "bhikkhunā nāma, bhante, mādisena bhavitabba"nti vatvā theraṃ vanditvā maṇivaṇṇe ākāse uppatitvā agamāsi.
32 tassa gatakālato paṭṭhāya jātasaṃvego divā uddesañca sāyaṃ uddesañca vācetvā pattacīvaraṃ hatthapāse ṭhapetvā paccūsakāle uddesaṃ gahetvā otarantena bhikkhunā saddhiṃ pattacīvaramādāya otiṇṇo terasa dhutaguṇe paripuṇṇe adhiṭṭhāya gāmantapabbhārasenāsanaṃ gantvā pabbhāraṃ paṭijaggitvā mañcapīṭhaṃ ussāpetvā "arahattaṃ apatvā mañce piṭṭhiṃ na pasāressāmī"ti mānasaṃ bandhitvā caṅkamaṃ otari. tassa "ajja arahattaṃ gaṇhissāmi ajja arahattaṃ gaṇhissāmī"ti ghaṭentasseva pavāraṇā sampattā. so pavāraṇāya upakaṭṭhāya "puthujjanabhāvaṃ pahāya visuddhipavāraṇaṃ pavāressāmī"ti cintento ativiya kilamati. so tāya thero pavāraṇāya maggaṃ vā phalaṃ vā uppādetuṃ asakkonto "mādisopi nāma āraddhavipassako na labhati, yāva dullabhañca vatidaṃ arahatta"nti vatvā teneva niyāmena ṭhānacaṅkamabahulo hutvā tiṃsa vassāni samaṇadhammaṃ katvā mahāpavāraṇāya majjhe ṭhitaṃ puṇṇacandaṃ disvā "kiṃ nu kho candamaṇḍalaṃ visuddhaṃ, udāhu mayhaṃ sīla"nti cintento "candamaṇḍale sasalakkhaṇaṃ paññāyati, mayhaṃ pana upasampadato paṭṭhāya yāvajjadivasā sīlasmiṃ kāḷakaṃ vā tilako vā natthī"ti āvajjetvā sañjātapītisomanasso paripakkañāṇattā pītiṃ vikkhambhetvā saha paṭisambhidāhi arahattaṃ pāpuṇi. evarūpassa dhutaṅgavasena vikkhambhito kileso tathā vikkhambhitova hoti.ekaccassa vuttanayeneva paṭhamajjhānādisamāpajjanabahulatāya kileso okāsaṃ na labhati, samāpattivasena vikkhambhitova hoti. so taṃ tathā vikkhambhitameva katvā vivaṭṭetvā arahattaṃ gaṇhāti mahātissatthero viya. thero kira avassikakālato paṭṭhāya aṭṭhasamāpattilābhī. so samāpattivikkhambhitānaṃ kilesānaṃ asamudācārena uggahaparipucchāvaseneva ariyamaggasāmantaṃ katheti, saṭṭhivassakālepi attano puthujjanabhāvaṃ na jānāti. athekadivasaṃ mahāgāme tissamahāvihārato bhikkhusaṅgho talaṅgaravāsidhammadinnattherassa sāsanaṃ pesesi "thero āgantvā amhākaṃ dhammakathaṃ kathetū"ti. thero adhivāsetvā "mama santike mahallakataro bhikkhu natthi, mahātissatthero kho pana me kammaṭṭhānācariyo, taṃ saṅghattheraṃ katvā
Nagasena was still a puthujjana bhikkhu, but he had mastered the Abhidhamma .
He gave a talk to a laywoman and she attained - and he attained immediately after, while he reflected on talk he had gven.
p. 21, 22 of Horners translation of the Milinda panha: (first section, giving the background of Nagasena)
Then the venerable Nagasena gave benedictive thanks
to that important woman lay-follower by means of a
profound talk on Abhidhamma that was supermundane
and connected with (the concept of) emptiness. Then as
that important woman lay-follower was sitting on that
very seat, Dhamma-vision, dustless and stainless, arose
to her: that whatever is of the nature to arise all that is
of the nature to stop.
And after he had given the benedictive thanks to that
> important woman lay-follower and was reflecting on the
> Dhamma he himself had taught (her), the venerable
> Nagasena aroused insight and was established in the
> fruit of stream-attainment as he was sitting on that
Then the venerable Assagutta who was sitting in a,
pavilion knew that these had both acquired Dhammavision,
and he burst forth into applause: “It is good, it
is good, Nagasena, that by one shot of an arrow two
great persons are pierced.”