@AvnerShahar-Kashtan I frequently use my own language for names, but in unusual ways, or just ways common to naming conventions.
One moment, I'll upload a couple of my maps.
Neither of them use any words outside my native language, although the first one employs a simple trick to make it seem that way, and the second one uses obscure words.
(Okay, the first one uses a single made-up word cribbed from a science fiction setting I liked at the time.)
My players spent six months living in Ossifica, Devo, Tesella, Incep, and Bas, and were never able to figure out why those words seemed so familiar.
But my main point is in the other names: Slurpy Marshes, Eternal Mountains, Southern Wastes, Black River, Snake Bone Hills.
They're totally normal words, sometimes even a bit slangy, but so are a lot of names. Whitehall, Jamestown, Portland.
Look at how ordinary words are turned into names in your language--I'm sure they are.
And maybe do a little digging for obscure words; "Otiose Bog" is just archaic English for "useless swamp."