I have an index for occupations (identifier + occupation):
I don't think mysql or your jvm settings have anything to do with this. I suspect one works and the other does not probably due to the SpanishLightStemFilterFactory.
The right way to achieve matching no matter the diacritics is to use the following:
Put that before your tokenizer in both index and query analyzer chains, and any diacritic should be converted to the ascii version. That would make it work always.