I have seen lots of servers lately that use the same sound files and maps from other games. Are these servers subject to legal action? Will it ever happen?
thats down to the owners of the copyright material to deal with, and yes some do like nintendo for example https://www.polygon.com/2017/7/14/15972052/pixelmon-minecraft-mod-shutdown
Would if you used the same character names from the game?
as i said, its down to the copyright holders to deal with, if they want to make claims against people for breaking their copyright they can choose to or not.
if you want information about the legalities of using names or anything that a company holds the rights to, speak to a lawyer, not a community based forum