French, Spanish, and Latin infinitives cannot be split because they are expressed by one word.

Is it OK to split infinitives?

Split infinitives should be avoided in formal writing. In formal writing, it is considered bad style to split an infinitive, but in more informal writing or in speech this has become more acceptable. ... Really is such a problematic word, it is best to avoid its use in writing and use a more specific adverb.

Can you have two infinitives in a row in Spanish?

There aren't two infinitives together in the English sentence. Nor are there two infinitives in the Spanish equivalent: Me he pasado la mayoría del semestre tratando de aprender. Remember, the word to that we associate with the infinitive is not really there in the Spanish infinitive.