Until that day, there unfortunately ARE niche applications. Fieldworks Language Explorer (aka FLEx) is software developed by SIL Inc for doing linguistic fieldwork (dictionaries, text, grammars, parsing...) in minority languages. There's nothing like it. There was a Linux version, but they ran out of funding; I've used it, but reportedly there are major bugs.

FLEx won't run under Wine, but I'll be trying this WinBoat to see if it works.

(You may have heard of SIL's fonts, which they also make freely available. The fonts work for a huge variety of scripts, including the Nasta'liq Arabic style that other fonts don't touch, and Burmese, which from a writing standpoint is truly crazy.)