I would like to ask @cdpatton to give his opinion about my research below if he doesn’t mind.
We talked about how “發菩提心” or “初發菩提心” seemed to be translated from bodhicittotpāda. What if “發菩提心” or “初發菩提心” wasn’t translated from bodhicittotpāda at all? What if the phrase was translated from something similar but not quite the same?
While I was searching for something completely unrelated to this topic, I stumbled upon Chinese EA 21.2 by chance, and I found this word: “覺意”.
https://suttacentral.net/ea21.2/lzh/taisho
“覺” seems to be equivalent to “菩提”, while “意” seems to be equivalent to “心”. “覺意” in EA 21.2 seems to mean “awakening” instead of “bodhicitta” where it’s used in the context of practice that is undertaken by disciples and the Buddha himself, namely: the absorptions, sense restraint, and detachment.
The seven factors of awakening in T 125 is also translated as “七覺意” instead of “七覺支” in both T 26 and T 99 or “七覺分” in T 99. I don’t think “七覺意” means “the seven kinds of bodhicitta”, especially when it’s explicitly explained in EA 39.6 and EA 39.7 as “the seven factors of awakening”. It’s also mentioned alongside the other 37 wings to awakening in EA 8.6.
What’s more, “覺意” is listed as synonymous with “菩提心” where its (菩提心) Sanskrit original is listed as “bodhi” instead of “bodhicitta” here: http://www.buddhism-dict.net/cgi-bin/xpr-ddb.pl?q=覺意.
This is purely speculative but “發菩提心” possibly wasn’t translated from bodhicittotpāda, and “心” wasn’t translated from “citta”. Possibly, “發” was translated from Sanskrit “utpāda” which means coming into existence or arising, while “菩提心” was translated not from “bodhicitta”, but from “bodhi”. Why is the word “bodhi” transliterated instead of translated? I have no clue, but the same thing happened with the word “Tathagata” in SA 1158 where it’s the only place in the entire T 99 collection where it’s transliterated as “多陀阿伽度” instead of the usual translation “如來”.
So, just as “覺意” in T 125 wasn’t translated from “bodhicitta”, but from “bodhi” where “意” is added to “覺” for some reason, in the same way, “菩提心” possibly wasn’t translated from “bodhicitta”, but from “bodhi” where “心” is added to “菩提” for some reason.
In other words, in my speculation, “發菩提心” possibly means “arising of awakening”, and “初發菩提心” possibly means “initial arising of awakening” or something like “inception of the arising of awakening”.
So, I would like to borrow yours and Ven Choong Mun-keat’s translations and change them a bit like this:
何等為信根?若聖弟子於如來發菩提心所得淨信心,是名信根。
What is the faculty of faith? If the noble disciple’s pure faith is that attained by the Tathagata’s arising of awakening, this is called the faculty of faith.
What is faith-faculty? If a noble disciple gives rise to awakening with regard to the Tathagata to attain a mind of pure faith, this is called faith faculty.
What do you think about my speculation? Is it sound?