Yes, spam and all of that isn't fun, at all. (The way you typed I'd partially consider spam. Would it have killed you to type it out in paragraph form or otherwise not type a few words every other sentence and space it down? It wasn't needed, thank you.)
But, Slycan put it very well.
Also, remember this is the Internet, these kind of things will be everywhere. Sure, should we sit here and just accept it? No. Is it annoying? Yes.
But a filter, the kind meant for curse words (I see a filter for curse words in FH as a big no, in my opinion. Although maybe a minor one wouldn't hurt considering I've seen some fairly bad language :/) just to block the word mate is not the answer. The answer is find the user, and block them on your in game block list. Or just filter the chats you want to listen to or not.
Due to a (sadly) lack of dimensions (We will not discuss this here, folks, not the place), you can't just skip to a different dimension and avoid the spam. Go to another map (I know, so horrible. I understand if you don't want to, but we've really not much of another choice, that or log out and take a nice walk, that works too.)
I'm sorry if you thought your post would have created some sort of.. big change in things here, but posts like these and complaints happen a lot, and we, and the staff, do what we all can to just deal with it. ;/
I don't know how the in game moderation works, but from what I hear it isn't the best so far? Either way, I'd just leave the staff to do their job, or if it is such a trouble, contact a forum administrator about it.
~ Kah