GetTypeFlags() - This gets the flag of a thing with getting the type of the thing automatically, which means if this is used for a player, like GetTypeFlags(player); it will get its actor flags making it same as GetActorFlags(player);
It's convenient that you do not need to specify what flag to get.
If used for projectile, like GetTypeFlags(projectile);, it will be same as using GetWeaponFlags(projectile);, not sure why LEC didn't use these anywhere.
SetTypeFlags() - This is same except it sets the flag instead of getting the flag. SetTypeFlags(player) is equal to SetActorFlags(player);
Because LEC decided so!