Is this a grave mistake in DN22 translation?
Even assuming attha.m could be equated to attā, it could not mean &quot;the not taking as self&quot;, because gama here means&quot;the going&quot;, so it would mean something like &quot;the going to self of pain and sadness&quot;.
Also atthaṅgama is a common enough word to leave very little doubt over its meaning:

“yato kho, bhikkhave, bhikkhu channaṃ phassāyatanānaṃ samudayañca atthaṅgamañca...&quot;
&quot;iti rūpassa samudayo, iti rūpassa atthaṅgamo...&quot;
“santāvuso, sattā sabbaso rūpasaññānaṃ samatikkamā paṭighasaññānaṃ atthaṅgamā...&quot;
&quot;ye hi keci, bhikkhave, samaṇā vā brāhmaṇā vā imāsaṃ dvinnaṃ diṭṭhīnaṃ samudayañca atthaṅgamañca...&quot;
“puna caparaṃ, brāhmaṇa, bhikkhu sukhassa ca pahānā dukkhassa ca pahānā pubbeva somanassadomanassānaṃ atthaṅgamā adukkhamasukhaṃ upekkhāsatipārisuddhiṃ catutthaṃ jhānaṃ upasampajja viharati.&quot;
&quot;yo tassā nirodho vūpasamo atthaṅgamo...&quot;

The entire PED section on Attha 2 is of interest:

Attha2 (nt.) [Vedic asta, of uncertain etym.] home, primarily as place of rest &amp; shelter, but in P. phraseology abstracted from the &quot;going home&quot;, i. e. setting of the sun, as disappearance going out of existence, annihilation, extinction Only in acc. and as ˚ -- in foll phrases: atthangacchati to disappear, to go out of existence, to vanish Dh 226 (= vināsaŋ natthibhāvaŋ gacchati DhA iii.324), 384 ( parikkhayaŋ gacchati); pp. atthangata gone home, gone to rest, gone, disappeared; of the sun (= set): J i.175 (atthangate suriye at sunset); PvA 55 (id.) 216 (anatthangate s. before sunset) fig. Sn 472 (atthagata). 475 (id.) 1075 (= niruddha ucchinṇa vinaṭṭha anupādi -- sesāya nibbāna -- dhātuyā nibbuta); It 58; Dhs 1038; Vbh 195 -- atthagatatta (nt. abstr.) disappearance SnA 409. -- atthangama (atthagama passim) annihilation, disappearance opposed to samudaya (coming into existence) and synonymous with nirodha (destruction) D i.34, 37, 183; S iv.327; A iii.326; Ps ii.4, 6, 39; Pug 52; Dhs 165 265, 501, 579; Vbh 105. -- atthagamana (nt.) setting (of the sun) J i.101 (suriyass' atthagamanā at sunset DA i.95 (= ogamana). -- attha -- gāmin, in phrase udayɔ atthagāmin leading to birth and death (of paññā): see udaya. -- atthaŋ paleti = atthangacchati (fig.) Sn 1074 (= atthangameti nirujjhati Nd2 28). -- Also atthamita (pp. of i) set (of the sun) in phrase anatthamite suriye before sunset (with anatthangamite as v. l. at both pass. DhA i.86; iii.127. -- Cp. also abbhattha.

So no, that part of their translations seems fine.