Hello Pitscheplatsch,
I am certainly changing many place names, especially street names. I'm doing so with the information I've gathered about how it should be done in the Valencian Community and which guidelines I should follow. The local user Jodi MF sent me the information I should know about the use of toponyms in this region, you can see it here:
https://wiki.openstreetmap.org/wiki/Ca:Comunitat_Valenciana#Topon%C3%ADmia_de_la_Comunitat_Valenciana
This together with the guidelines of the AVL (Acadèmia Valenciana de la Llengua) regaring the correct use of the Catalan language in this territory, along with different laws stating that Catalan language should have preference in the areas where it is spoken, is everything I used to make the changes, always taking into consideraton the actual and real use of what I'm correcting. 
Let me know if you need more information.

Kind regards,
Alex