Are you trying to say that a 4 month residency in spain, that is directly afterwards interrupted without any further available property should lead to a center of someones personal life?
Explain me please where the center of interests should come from, because leaving the country and quitting the residency sounds more like a case for the exit taxation and not for the center of main interests. In the end it will come down to cyprus, france and spain fighting with each other who should get the right to tax since they all have treaties with each other. I dont see any other country being successful than the one country where someone also spend 4 months but maintained a permanently available residency during the entire year, not like in the others.
I do see the point that working from spain may change the situation. Does anyone has first hand experience about this?
You are looking at taxation by each country from a wrong perspective, these three countries will not "fight" against each other to proof you have to pay tax in their jurisdiction and not the other country, they don't care about other countries. All three if they believe they have the right to claim tax, they will and at that point DTA comes into place. All three can make the same claim and reverse burden of proof is to you.
Sometimes they are right, sometimes they are wrong. If they believe they have a reason to tax you and it's worth it for them to go after you, they will proceed and send you the tax claim, which you can appeal in writing by proving proof.
At that point if they believe your proof is sufficient they will accept it, but very often they won't if they already started investigating you.
In any of the cases it is best to have an international tax lawyer at hand in each jurisdiction, anything said here on the forum can share ideas, experiences and opinions, but every situation is different.
EU countries exchange all information they have with each other, either automatically or on request, just as they can easily block your assets in EU until the matter is resolved in court. EU countries will easily assist with this, this is were the EU is an union.
Within the EU you can freely travel, so it is more difficult for them as well as for you to proof where you reside unless you have a permanent establishment and are already a tax resident and obtain your income from working/living there.
It would be interesting to hear if anyone managed to be a perpetual traveler in EU and managed not to pay tax anywhere.
In my opinion it is best to have one place you are a tax resident in EU or just stay out of the EU most of the time and live in countries that don't chase/enforce aggressively taxation on worldwide income (keep your income out of this country) or even better live in a country that doesn't tax foreign income.