Well,
don´t know why and how, but today I got the taxiway number boxes displayed on my P3Dv4.3.......!!
I had first a problem using the parking customize function, Couatl crashed (!) and I couldn´t start it again. So I reinstalled GSX L2 ( keeping Addon Managaer installed ), and after the new start of P3Dv4.3 I saw the taxiway number boxes for the first time!!!! Got all my customized airports with such numbers, they were : LSZH, EDDM, LIML.
Hereby a screenshot of gate E58 LSZH, short after my editing of the taxyway.
Regards, Pit.