I have a mi9 phone. I see that for this phone only have a China versión estable. IS It a good idea to install this versión un Spain?
What do you mean by China version?
For MOST devices Xiaomi.eu ROMs (Weekly and Stable) are build based on CN firmwares, but adapted (as the name says) for Europe
Eu Weeklies are based on Xiaomi CN Beta weeklies, those that are considered good/stable enough (with minor fixes, if needed) get released as Stable
Read user opinions and decide if you want to try or not (it's not the matter of Spain or Europe but about the new MIUI 13)
PS:
Btw, in the OP post #1, in the table, it's still empty/NA (-) for Mi 9.
And if you go to downloads servers, there is no MIUI 13 ROM yet for Mi 9
If you want, you can find Xiaomi.eu Stable (another topic on this forum) but MIUI 12 for Mi 9 (I'm similarly using/responding you from my Mi 9T with Stable MIUI 12.5.2 - also no MIUI 13 [yet])
Simply because there are no CN Beta weeklies for Mi 9 models - when (if?) they build, we will get MIUI 13 but with A11 (not A12 as the new models)