The original MapOSMatic project used Transifex as its web translation frontend.
As my fork diverged over time, and as Transifex became less open, I have been thinking about an alternative for quite a while now. So far none of the alternatives I’d been looking at really convinced me though.
Now yesterday I stumbled across Weblate, and almost fell in love immediately. Almost everything I ever wished for, supports self hosting, and is even easy to setup.
So translations can now be maintained on https://translate.get-map.org/projects/maposmatic/
The only thing from my wish list that’s still missing now is OpenStreetMap OAuth support, but as the project already supports other OAuth providers this should be easy to add over the next weekend, if not earlier.