And if you ask me, as an outside observer not as an expert in Belgium internal intricacies, I think your system is fucked up because too much importance has been given to the differences in languages from the outstart or to some alleged or real differences between communities.
I don't understand for example why it isn't possible to vote for the party you wish and you are tied to the community you are supposed to belong to. If this weren't this way, there would be no "special" rules for the French living on "Flemmish" territory. (Which I believe has been a point of contention)
Since you are in one single country, you should all be able to vote for the same parties, regardless of its origin.
After all, (and I read French you know and can read what's written on forums of LeSoir or similar), a Wallon may wish to get rid of these detestable Flemmish and vote for a Flemmish independentist party.
As far as your example on immigration is concerned, there is nothing unusual in one country/ State to have diverse opinions on how money is spent. You are making a huge deal out of the fact that "Wallonia who votes A" wants this while "Flander who votes B" wants the opposite. Since both Wallonians (?) and "Flemmish live in the same country, why not replace the first term of the equation by "the Belgians" ? If you do, you get the standard situation of any Western democracy ...
IMO, it is too much stress on particularims which leads to the present situation.
Focus on local particularism is a sign of lack of tolerance - or let say lack of "inclusiveness".
So, I don't have a "solution" for you, except maybe to cool down a bit and try to look at the situation in a more relaxed way. I agree with Stillalive here : open businesses in Wallonia to give jobs After all, the Flemmish have a superiority over the Wallonians that they usually speak their language better. Instead of pointing to the deficiencies of the alleged adversed community, try to work together.
This is the fondament of European unity you know - create concrete solidarities - Work together to live together.
"Europe will not be made all at once, or according to a single plan. It will be built through concrete achievements which first create a de facto solidarity."
Schuman Declaration - Wikipedia, the free encyclopedia
A lot to be said still about small States v. large States, the pointlessness of a conferederation and the private ambition of politicians - and of course being the prime minister of Belgium under the present circumstances would be a political killer, not an achievement !!