Is it possible to add a Keyboard Language not in the list?

yes, similar to this person here(but Hebrew as the language):

I’m not asking to add it officially even though that would obviously be welcomed,
but asking for a way/solution to add it.

apparently Anysoftkeyboard couldn’t get added to the Sailfish apps keyboard,and maybe it’s only meant for Android apps.(or i missed something in it’s initial setup).

the closest solution i found was from this thread:
https://together.jolla.com/question/12370/support-for-hebrew-language-squares-when-receiving-hebrew/
pointing to this package:
https://openrepos.net/content/schturman/hebrew-vkb-2-arrows-toggle-en-he
which was last updated in 2014.
so i don’t know if it’s still working.