The game is very fussy on this issue with regards to the coding. I'd kept my original RTW v1.2 EDU file, and soon realised that Pontic generals weren't upgrading properly. Had to do a bit of re-tweaking to make them work properly, which also involved the usual updating of the enum file, export_units and also export_descr_sounds_unit_voice.

From the responses already, it sounds as if they've fixed this Pontic general issue in vanilla versions. I've recently seen the Egyptians using their post-marius reforms general's cavalry, which is basically the egyptian cleruch model used for Nile cavalry. But as mentioned, I've kept the text file from v1.2 and converted it upto v1.5, not sure if they've changed it again in this time.