I upgraded from 2.6.3 to 2.7 about 8 months ago… and I just noticed… the Translation feature is gone? Or is there a way to turn it back on?
Check Spark > Plugins menu. You probably just have to enable it. Works here.
Ah, there it is. Anyway to have that automatically enable at install? Or do I have to manually enable it for every client? 
I don’t know of a way to do it automatically. Maybe it is related to another issue i ran into recently when trying to tweak Translator a bit.
[SPARK-1610] Add translator dialog to the group chat window - Jive Software Open Source
It seems that Translator plugin was pushed outside of build script and maybe there is some other place in the source prohibiting it from automatic install on a fresh profile. Though it seems it works ok, but at some point it was broken i think and probably then it was disabled.
Found the ticket responsible for Translator removal [SPARK-1456] Remove Translator plugin - Jive Software Open Source
So does that mean even if I install the translator plugin, I should not expect it to do anything?
No, it works actually. Though it stopped working at some point. But, Google has made API available again, apparently. It is still bundled with Spark, but it is excluded from the build process and some packages are missing, so it can’t be changed/improved. It just stays in that ~5 years old state. Hopefully it will continue working