I've used quite a few of the Testor/Model Master lacquers now over enamels of various kinds with no problems at all as long as the enamel is dry. The stuff seems to be very mild.
Haven't used that many Tamiyas so far but what I have used, same story.
I've discovered that some Krylon, Walmart, and Rustoleum paints that say "fast drying enamel" on the label are actually lacquers, and some of them are pretty hot, too.
When in doubt, there's no substitute for testing, preferably on the plastic from that very model. I like to use the undersides of interior tubs and the topsides of chassis--places that won't show--for this.
I've found that testing on plastic spoons doesn't always work. I've had paints (some Krylons) that laid on the spoons beautifully, but would eat kit styrene.