Hi aaesteve.
An interesting point about the VFR pilots losing situational awareness but perhaps it might be better for them to be out of the loop (they can see and avoid) than larger, less manouverable aircraft in IMC? That said I suppose most of the VFR aircraft will be PPL's and it's difficult to insist they communicate in English. No reason why the commercial traffic can't though and it's those aircraft I am most likely to encounter which is why they worry me.
I take no pleasure in denigrating a group but it has to be said Spanish ATC gives me cause for concern. Please don't take that as an insult, it's an observation based upon my experience. Nowhere is perfect but they do seem to lose the plot more often than some others.
Their most infuriating practice is to ignore aircraft checking in and dealing with a 'later' one who calls in Spanish. What is the solution? More money and better facilities for people like yourself perhaps? Clearly you and your fellow trainees have a better grasp of the language than some of the controllers I have had to deal with and we can only hope you graduate soon.
Good luck!!