It's cool that the Disguise Self spell works that way. For the sake of immersion it should, but you never know how much work the devs have put into things like that.
As a non-gaming software engineer, it should be fairly simple as long as it's planned properly. Basically, you'd have your
Actual Race, set at the start of the game, and your
Apparent Race, which is normally the same as your actual race but can be changed by Disguise Self, etc. Anything that changes based on how you present yourself (e.g. appearance, dialogue options) would look at your
Apparent Race; anything that doesn't change (not sure if we're certain that anything doesn't change, but I'll say racial stats for an example) uses your
Actual Race.
Anyway, that way you get all the changes you'd expect, with very little extra work. They could have any number of different
Apparent Races, e.g. if one spell changed your appearance but not the dialogue, or another spell let you talk like a drow while looking like a gnome, or whatever.
