Are such acronyms suitable as tag names, or should the maximum tag length be increased?
A good rule of thumb for using abbreviations in your tags is to use them if you think that people who see your tag will be able to tell what it is without extra context. If not, than it's not a particularly strong tag.
according to wikipedia, there are a lot of things that have an abbreviation of
But if you go to the Eurovision Song Contest page, the first thing it says is:
"Eurovision" redirects here. For other uses, see Eurovision (disambiguation).
Eurovision might be an even better tag.
Also, I don't know if
Eurovision song contest really needs a tag. It doesn't really sound like a catagory of question. It kinda feels like the foreach tag on StackOverflow.