Is textarea always accesible throught textarea#content in wordpress dashboard for a specific page?

If someones stumbles on the same question. The short answer is yes.

I’ve tested around ten totally different themes and I didn’t have any issue with any of them. I have only tested when using “Classic editor” (not Guthenberg) so it may differ if you use Guthenburg because it’s a another way of retrivering info etc.

I cannot say yes with 100% (because I’ve “only” tested with 10 different themes) clarity but 99,9% probably 🙂