as far as i know and tried myself, the "add timer option" works if there is a timer actually. tried it on aggravating courier missions and it will add minutes to the counter randomly or 1 minute if i recall correctly.
which catacomb are you referring to? the auditore family tomb? you can beat that one without cheats, trust me. i didn't really use "timer" in tombs cuz i wanted to beat that w/o cheats but i know the timer option works basically. as for teleporting i have only tried that once and got caught in nomansland so i never used it again.