[Q] HTC E8 - A ROM to contain all languages topic

Hi.

I have a HTC E8(Single sim) that was purchased in Germany.
It runs stock 4.4.2.
For some reason, the language selection screen has less languages than the general Android. For example, it lacks Russian.
Should I reflash the ROM to get it ?
What I already did:
Unlock the bootloader - using the HTC dev site.
Flashed the twrp - didn't work, after a reboot I still see the stock recovery (should I S-OFF or something?).
I didn't use the "Battery out method". I mean I did boot to the stock ROM after flashing TWRP. May be my ROM overwrites the recovery on boot :(.

Can I somehow add the language files to the existing ROM ? Should I have TWRP for it or can I flash it with fastboot ?
I am OK with any generic or custom ROM that doesn't have any bugs running on E8 (CM doesn't support E8 it seems :().
I don't need root. I only need the language.

All help is very appreciated.
Thanks.