Years ago when I was a superintendent I failed a final inspection because the inspector said the regulator was too close to a foundation vent. I cannot remember what he told me about clearances and came across a propane regulator roughly 3’ maybe 3.5’ directly under an operable window that has a window ac installed in it, and maybe 3 ft from a foundation vent today. I have tried googling and I cannot find requirements on this so maybe he was pulling something out of his rear. I can find plenty on propane tank locations but nothing on regulators. As far as I can tell there is no propane tank on site that I can find anywhere. Also not that it really matters there is nothing inside the house hooked up to the propane line.
This may help you here;