Hi Marc -
Vanicek provides a few more details. It seems the border troops were committed a few companies at a time - probably due to the gradual escalation in the intensity of the action between 1792 and 1796 coupled with the Turkish threat, the Turkish war being a recent memory. So for the Wallachs, 3 companies from each of the two regiments formed a combined "1st Wallachian" battalion sent west in 1792, later two additional combined battalions were formed. The same holds with the other grenzers sent west, so the numbering and naming are not by regiments but rather according to the regional groupings from which the companies were drawn (Wallachian, Szekler, Banater, Slavonian, Warasdiner, Banalist, etc). so there are units like the 8th Slavonian Grenz battalion identified.
At Aschaffenburg on 7 September 1796 Vanicek notes the following border troops present with Oberst Jellacic's advance Guard under Kray:
1st battalion Grenz sharpshooters (Grenz Scharfschutzencorps)- drawn from Croatian and Slavonian grenz regiments
one combined battalion Wallachian Grenzers
one division "Barcohusaren"
Hope this helps!