Well... I solved it... It was the tv's default (internal) settings fault, nothing to do with Recalbox. After all it was very easy to fix.
It seems there are many versions of PAL depending on the territory blah blah... color subcarrier varies from european PAL to american PAL, different frequencies blah blah... ok if you are interested read wikipedia, its all there.
So, my TV is southamerican... Rpi comes from UK... a continental PAL conflict may be
So I entered the tv service mode (from the remote control: "power (off)", then "display", then "5", then "vol +" then "power (on)").
It starts in "GEOM" category... with buttons "5" and "2" you change category. Go one category down (press "5") and you should be in "OPTB" category. Then change item with "1" and "4", two items up (pres "1" twice) and you should be in item "002 OPB2" which value in my set was defaulted to 43 (PAL/NTSC tri-norma).
All you have to do is change this number with buttons "3" and "6" to 40 (PAL/NTSC multi).
Save the new settings pressing "muting" then "0" (zero). Be careful as it writes into memory. Theres a possibility to reset to defaults... its all in the service mode manual and its just googling it.
Well... hope this comes handy for someone someday!
PS: To whom may know... Are PAL colors like washed out compared to NTSC? Because it seems like that to me... just a little but noticeable