Hopefully I can explain my predicament properly. I'm having trouble thinking up names for the gods/goddesses in the fantasy book I'm planning to write. I didn't want to just use a name generator online and I also didn't want to give them the Latin translation of their element/area of expertise as their name (because I want to be as original as possible and stay away from cliches). So I thought, hey, how about I give them names from my own culture? I'm half Lithuanian, half French, but Lithuanian culture is what I've grown up in. Anyways, I want to give the God of Fire the name Gaisras, the God of Air/Wind the name Vėjas, etc. But, I don't really feel the need to base anything else besides place names off my culture. Lithuania has amazing architecture, religion, mythology, etc, but I don't want to use it in the work I am planning. Is that okay?
Seems okay to me - the vast majority of English-language readers will have no idea what the names mean!
I think it comes down to a few factors. Do they become gods? If so it is a completely logical conclusion that they had normal names first. If they are born gods it can still work. It is your world. The thing to do is to write it so well that you give these characters and there names meaning. Instead of the names innately have meaning.
It kind of depends on who gave these gods their names. Are the gods in that world canonically real, as in, do they really exist at all in the story, or are they just assumed to exist by the people? If the former, did the gods reveal their names to the people, or did the people simply name them? If the gods named themselves then you can name them whatever you want, but if the people named them then it would make sense for them to have names that are linguistically similar to their language. What I mean by this is that it wouldn't really make sense for them to name the gods with Lithuanian names if their language doesn't sound anything similar to Lithuanian. Judging by what you've said, I'm guessing some of their culture and language is somewhat based upon Lithuanian culture/language, so it would most likely be fine.
Unless your gods are real, they will be named by the people in their language. Thus the Native North Americans had the Thunderbird. If your gods are real, and reveal themselves to the people, it's more than likely that the names which they call themselves will be unpronounceable to human tongues (as in the artist formerly called Prince!), so those names will be transliterated into the local human dialect. Or the local humans will call a god with a REALLY unpronounceable name e.g."the red one" - in local (diafol coch in Welsh - which could be concatenated into a single word). I remember one SF story where the locals had deified a spaceship which they called Orure, which was their transliteration of the spaceship's name Aru Re = Bird of Mars. Incidentally, if those names are transliterations of the sound, it could be that it sounds similar enough to another word that the etymology of the god's name becomes confused, and the god then becomes attributed with characteristics associated with the word it sounds like. e.g. The god's name is transliterated as R'mainee; this could be confused with being Romany; or of Roman origin; or he's the god of constant movement - roaming; he's the god of changelessness - remaining. This happened in reverse with the Tower of Babel, which has entered English as the verb to babble - a constant incomprehensible chattering.
If you're familiar with the Witcher books, lots of the supernatural beings there seem to have names that have been borrowed from the Slavic mythology. I think that's fine. Granted, if I spoke the language and found the name that's used in my language to refer to the god of forests or something to be in the book the god of fire, I might find it a bit amusing.
It's great that you want to pay homage to your Lithuanian heritage by using it to name the gods in your story. If you don't want to use that part of your background in the naming of anything else you don't need to though. Do whatever feels/sounds right to you. As far as the names go, my suggestion to you would be to try to change up the Lithuanian words a bit to make them your own, either by shifting vowels or consonants, or combining two or more words together. The names would still be derived from Lithuanian, but this way if any other Lithuanian ever reads your story it won't just seem like you named the fire god "Fire." So you could take "Gaisras" and turn it into "Kaisras," K'sras," or "Gaiseras." Maybe different cultures in the story will call the same god by slightly different names. Or you could combine "Vėjas" with other Lithuanian words like "oras" (air, atmosphere) to come up with "Vejoras" a name that will still imply everything you want it to, but won't just be the word for wind or air