Then set up hotkeys to do that? I'm not seeing the issue and this definitely isn't a bug.
I don't think there's a way in the UI at least to accomplish this in a single hotkey, but you can have t1 factories on "w," t2 sup factories on "shift w," and t3 on "ctrl w" for example. There's not a native way to have the same hotkey do different things based on the level of the engineer selected as far as I know.
If you manage to get one hotkey for all support factories and t1 factories then the first ones that show up will be the highest level available to that engineer, which is close to what you want.