How to earn medals like trying to improve quality and having a prominent contribution to the game? Should we join the group of game translators for this? Also is the full galaxy explorer medal to travel the entire galaxy or do we have to go through all the stages in the game?
You mean bug medals? All you need to do is spot bugs in-game and report them to IA on the forums. If you want to catch bugs, try looking everywhere in the game (options, missions/waves, etc). And if you find one, report it quickly because some other forum people are really good and/or quick at that.
As for idea medals, just make suggestions (ideas) and maybe one of them would be approved and added in-game by IA. But always take as much time as needed to build your suggestion well, before posting it, and try being as original as possible.
Only the entire galaxy. Everything you can visit in the galaxy map counts, but missions do not count (20k+ missions would take years to complete).
You can check your galaxy exploration (excluding missions) here:
the only truly unobtainable medal now is the early access medal
it would definitely become rare in the upcoming years
Future completionists will hate that.
This EA medal could have an alternative for playing on the beta server when it finally gets added.