That unit of Walachian troopers was indeed part of Archduke Charles troops he left, after the siege and the taking of the Kehl Fortress, to besiege the Huningue Fortress, under the command of the Prince of Furstemberg, at the end of Year 4. The Huningue fortress itself was placed under the command of the generals Férino and Abatucci (who was mortally wounded during one of the counterattacks of the French), and capitulated after some weeks.
But I didn't find exact information to which unit those Walachians belonged to.
Groetjes en hopelijk snel tot ziens.
Hoe gaat het met jouw gezinnetje, en met de jongste ?
Ik heb het ontzettend druk met mijn tentamens.