Roguelike Dungeons -- Fnar's Edition adds language support for its custom items since version 2.4.5.
The initial idea of this Resource Pack was to support Vanilla clients who join servers that have this (or later) versions of Roguelike Dungeons -- Fnar's Edition mod, so they can see its custom items' Name in their language.
(Item Lore will remain in English, because of Vanilla Minecraft limitations).
But this project can increase the supported languages to as many as possible!
When Fnar finishes RLD for newer Minecraft versions, I'll try to upload its corresponding Resource Pack.
Modded Minecraft 1.12.2 users:
If you have Roguelike Dungeons -- Fnar's Edition in your Minecraft instance, its custom items' Lore (AKA flavor text) will also be translated!
For Novelty items custom textures, download CIT for Roguelike Dungeons! (Requires Optifine).
Fnar granted me permission to publish this Resource Pack, to expand language support for RLD <3
If you want to contribute adding your language to this project, feel free to make a PR!