As far as I have observed on the [github repository][1] , the commits from translatewiki.net are triggered *manually* by user [siebrand][2] estimaded estimated once or twice in a month.
And about the wrong text in routing instructions: it is quite possible that this text is coming from OSRM sourcecode. So dig into that repository on github to get some hints about translations there.
[1]: https://github.com/openstreetmap/openstreetmap-website/commits/master
[2]: https://github.com/siebrand