I have the same Meeus book. It's been a while since I read it, but my impression was the signs of longitudes being turned around was not unique to his book, bu

I have the same Meeus book. It's been a while since I read it, but my impression was the signs of longitudes being turned around was not unique to his book, but was rather a convention throughout astronomy, so you could expect to find whatever other books you're recommended would have the same convention. When I was contemplating my own implementation from that book my sketchy API design just included a mandatory extra parameter to accompany such numbers, which would explicitly indicate whether the astronomical or other sign convention was to be used.