Possible meanings are 1) Paul is exaggerating for the sake of effect and does not believe that people speak the language that angels use or 2) Paul thinks that some who speak in tongues actually speak the language that angels use. (See: [[rc://en/ta/man/translate/figs-hyperbole]])
The phrase "to be burned" can be made active. AT: "I allow those who persecute me to burn me to death" (See: [[rc://en/ta/man/translate/figs-activepassive]] and [[rc://en/ta/man/translate/figs-explicit]])