it’s quite a good idea actually to have inter-instance communication! i will have to put more thought into it, but definitely added to the TODOs

the like system is a sort of trust score, kinda like stars in ultimate guitar, so the community can downvote entries and that will help filter out bad content

I think it is certainly possible to do , but I think it is not really something interesting for most people. I therefore think that it is easier to handle it all on wikimusic side, also considering permissions and content per instance, etc