I haven't run into any problems on my 80's Gretsch. They used self tapping screws into the lugs. As long as you leave them alone they should be fine. If you take the lugs off for some reason you'd need to exercise extra caution and maybe try to keep the same screws with the lugs they go to. If you're careful there shouldn't be any problem.
That all kind of applies to any vintage lugs. Even the ones with tapped holes can break when backing a screw in or out.
I did take the lugs off my 1987 USA Customs back after I bought them (to stuff them with cotton) and I didn't know there was a problem, nor did I experience any trouble despite not being particularly careful.
I think that modern Gretsch imported hardware no longer use the self tapping screws, that was just at the tail end of the American made hardware.