sailmaker: Definitely not Italian (which I speak), but could be Spanish (which I don't).
renloz: Is not Spanish. To me it sounds eastern european and according to this
site it is some kind of "Bulgarian yogurt" mixed with english and the girls voice in the overture is actual Bulgarian. In that page it also says that some part of it they kind of say "just do vite….John Wayne, ajuste le hit", vite is the French word for quickly and "ajuste le" is "adjust the". So imo they are english and french words, that don't make any sense, pronounced in a way that make them sound like Bulgarian (at least to the singer/composer) and due to that nearly incomprensible to French and English speakers.
And for a laugh see this
video. Quite an amusing interpretation.
I assumed it was French as well but in fact it's just a few European langauges jumbled and mixed together, as you suggested, but cut up and played in different ways. Kind of like Sim-speak.
That song is great - the game's original installer really drove it into your brain. I really like Home Sweet Home as well.
EDIT: That video just made my day.