Yes, it's a MediaWiki thing to auto-capitalize the first letter, but no subsequent letters. You can see this all over Wikipedia.
In fact, this MediaWiki feature controls the "house capitalization style" of Wikipedia, where article and section titles are capitalized in their first letter but no subsequent letters --- for example, "Climate change denial", not "Climate Change Denial".
When I started editing the Spiral Knights wiki I had to adjust to the capitalization style here --- for example "Battle Sprite", not "Battle sprite".
Of course, proper nouns requiring capitalization are capitalized on Wikipedia. If you search for "Grand theft auto", you are redirected to "Grand Theft Auto". So yes, the standard way to deal with this issue seems to be manual redirects.