Well, most tax advisors are useless. In the majority of EU countries you just register that you live abroad by giving an address abroad. There is no requirement that it is your
tax residency (
tax residency is anyway determined in hindsight and is not obvious to determine). A small minority of EU countries like Italy requires you to prove that you live abroad in order to register as a citizen
living abroad - but again that is not the same as tax residency.
Yes, if you re-enter from a tax heaven, some countries can try to investigate you. And it should be fine as long as you really havent been a tax resident in the country you re-enter to. But well, cant totally exclude that some southern european country's tax agency would use the fact that you havent been a tax resident anywhere against you, they can come up with all kind of stuff.
So if you plan on re-entering a country with a difficult tax agency doing their own lose interpretation of the laws, best to read up on actual cases of re-entering to that country, and maybe register yourself in a non-tax heaven country before re entering if that helps.
But in most EU countries, you just register that you live in the country again, that's it, you dont have to demonstrate anything, just start paying tax from the tax year you re-entered.
And my experience here is that Ive lived in 6 EU/EES countries and moved back to a country I was previously a resident in 4 times in total I think. Never had any issues at all, and never had to demonstrate anything.