Here's a novel idea: if you're going to go to the trouble of commenting why not try to adding some actual content to the discussion? If you want post information-free snarks there are plenty of sites other than LWN that would like to read them. What advantages do you see in keeping translations in the project VCS? Please try actually thinking about it instead of spouting CompSci 101 cliches.
It's obvious why developers like to use VCS's for source code. It's not at all obvious to me why developers would want to bother putting translations in the VCS. I've maintained translated FOSS projects for a long time, some as long as 14 years, and never one time in all those years have I ever even considered wanting to go back to an earlier version of a translation file, or diff two versions. What's the point? I don't know those languages so the differences are meaningless to me. I'm not going to apply patches to the translation files myself: that's why there are translation teams and any change I make directly just subverts their work. If users send me translation patches I direct them to the translation teams so that work can be coordinated there.
I have more than enough on my plate without managing translations as well. To me it seems simpler to let the teams choose their own methods for managing the translation and I just take the results, rather than trying to create an interface to every VCS some developer might want to use so they can keep their work in my tree.
I did suggest one reason to prefer translations in the VCS: if you manage multiple release branches (not development branches) and you need to allow for updated translations of older release branches. Many FOSS projects (and translation projects) don't bother with that, however.
If you'd read my message and looked into Gnome development you'd know Gnome projects use git. When I want to see what's changed upstream since my last merge I check the log and there are tons of commits for translation changes; often so many that bug fixes, features, etc. are lost in the noise. If you have a "better tools" way to fix that I'm interested.