Is it ok to edit musicbrainz.src file ?
Yes, absolutely. If you intent to share it, please make sure you have the capacity of maintaining it.
I am not going to share it.
I usually get tags from musicbrainz using mp3tag. Then I have action group which I execute after tags are loaded. This action group removes some tags which I dont need and then also rename some other tags. I just thought that maybe it would be better idea to change the src file so that tags are written with names I want the first place.
I just wonder if modifying this file is not recommended for some reason. Or if it is overwritten when istalling new version.
Yes, it gets overwritten on updates, so just use a dedicated name for the file.