Due to the length and low profile of these coaches, Roco decided to offer the reduced scale length Fleischmann coaches for the AC models of the HVZ (Hauptverkehrszeiten) double deck coaches.
The coaches have a more significant overhang in curves and with the low profile, are more likely to impact against rail side objects like turnout indicators, catenary masts, signals, etc.

That said, my recommendation for use of these coaches would be to outfit them with current conducting couplers and to run the power from the locomotive.
Tillig does not make an AC slider for these models. As far as I could tell, the model does not specifically have a place where a slider could be applied, as most Roco, LSM, ACME and other coaches do.

I will look into this and see what I can find

There may be some posts on Stummi or Drehscheibe on line by people who may have tried to convert these coaches for AC.

Regards

Mike C