Finally I could slice successfully, but I had to do a lot of handcrafting with all the configuration files. Cura 5.4 was working flawesly but 5.5 and 5.6 has been a nightmare.
First, there are no variants so any profile that you try to set goes to a empty variant.
I've loaded the variants, qualities with some prebuild configurations, intents, extruder, and the problem with the definition finally, if you take the FLSUN SR definition, and the FLSUN V400 set the same amount of overrides, that means, nothing... The Slicer fiflsun_v400.def.zipnally executes, the problem here is that the precalculation of the speeds, and other stuff are lost.
I've attached my deffinition file and a prove that the process has finished, after weeks of fighting against that.