Not necessarily, but occasionally, the powers of the god-names can interfere with each other. I have learned this through person experience. Though, as for harmful effects, no. It can be useful to work with one god name for a chakra, another for another, and one god name for a certain portion of the aura.
For instance, if you are using 'SIN' on the 6th chakra, I recommend sticking with SIN for some time so the workings have enough time to generate their corresponding effects, and so you do not have to worry about interference.
However, interference can also be avoided through affirmation, because affirmations are specific.
As for the names from different cultures, I would say no it is not harmful. Personally, I find it best for a person to have a certain affinity for the cultures but it is not necessary. I have used Sumerian, Egyptian, modern names, Greek, Roman, Japanese, and have had no untoward side-effects.
Hail Satan