I read somewhere that there was to be a new livery for the 628 so it could run on the new Austrian route. I checked the liveries for the 628 and couldn’t find a DB livery, nor were there any options to select this in the Timetable mode on S-Bahn Vorarlberg. Any info on this and an approximate eta for it, if it does come?
It's AI only on Vorarlberg, so it will not show up in the menu. You'll only be able to use it in Scenario Planner and Free Roam until a route using it comes out.
DB RED 628s are only AI on Vorarlberg. You can not use those trains to run service in both Niddertalbahn and Vorarlberg. On Niddertalbahn they will not substitute for the mint livery.
The current Verkehrsrot and Lichtgrau DB livery was introdeuced in late 1996, on new-build rolling stock, and was slowly applied to existing vehicles beginning in 1997. So while technically just possible on Linke Rheinstrecke, most unlikely; and completely impossible in 1992 on Niddertalbahn.
You can go into the timetable mode, select to spawn a new train, and then search for "628 VR", that's the red version. You can spawn it and play it that way, but at the time it is not possible to play it in "official" timetable mode or scenarios on any of the routes.
It would definitely look better, but they'd probably have to redo the entire timetable since the 628 is much slower than the 612.
in TSW3, there was a mod, that substituted the BR 612 with the BR 628. I had no problems staying on time. But it would probably need resimulating the timetable etc, and changing it, which they don't like, because then some people would complain, they had the services, but don't anymore, because they don't own NID.