In an action this day the 1st KGL Hussars led by Captain Krachenberg attacked and drove back a troop of French dragoons of the Provisional dragoon regiment, claiming to have killed three officers and 10-15 troopers (Beamish p.277). A search of sources on the internet gives several stories but vastly different. Often the term "cut down" is used, which may indicate killed but also could mean exactly that. Cut down by a sabre and wounded. The British army was in retreat and therefore did not hold the ground after this skirmish, which may be why the claims are a variance with the facts.
Three officers are indeed identified, sous-lieutanants Jacques Mimin, Libault and Coutrez.. However Mimin is the only officer mortally wounded, and that by a cannonball. The others appear to have suffered wounds but not died of these. Libault survives and is wounded at Waterloo. Sgt-Maj. Louis Engle cut an officer from his horse and took a second prisoner (Beamish p.499). Does anyone know what were the actual dragoon casualties in this engagement? One French officer was captured was this Libault or Coutrez?
http://www.planete-napoleon.com/docs/DragonsEspagne.pdf
https://www.2dragons.be/historique.php
I cover this action quite extensively in my book Wellington's Light Division in the Peninsular War: The Formation, Campaigns & Battles of Wellington’s Famous Fighting Force, 1810. Frontline Books, 2020. Pages 152 - 159. You are quite right about the casualties being a bit of a mystery.
Casualties were one-sided. Lieutenant Shaw reported the division had five men wounded. Lieutenant Tomkinson reported that ‘. . . our loss, Hussars one man killed, three wounded – two horses wounded. The 16th lost one man, two horses wounded; had they brought guns, we should probably have suffered equally.’ No casualties were reported for the infantry.
The French took many casualties, although the exact number of soldiers killed and wounded is unknown. The number among officers was quite high. Lieutenant De Gelorès of the 3rd Hussars was wounded in the left arm by a sabre. In the 1st Provisional Dragoons Sous-Lieutenants Courtrez (of the 1st Dragoons), Jacques Mimin, Libault and Coutrez (all of the 2nd Dragoons) were wounded. In the 2nd Provisional Dragoons Sous-Lieutenant Leleu (of the 4th Dragoons) was wounded.
Sous-Lieutenant J. Mimin died of his wounds in Salamanca on 15 July. General Sainte-Croix reported to General Junot that: "The 2nd Dragoons continues to work wonders. Sous-Lieutenant Jacques Mimin distinguished himself in a reconnaissance carried out under the cannon of the fort. He cut his right arm with a cannonball and died of this wound at Salamanca Hospital on July 15th. This officer is one of the bravest soldiers counted in the 2nd Dragoons; He was known as a dragoon at Heilsberg and Friedland, and he was still distinguished on the day he fell gloriously before the enemy. His brother Jean had died in Portugal on May 8 previous. Lieutenant Libault, injured, is cited in the same case."
I have no record of a French officer being captured.
BTW: if you are interested in the fighting between the cavalry outposts in the area Chapter 7 "The War of the Cavalry Outposts, July 1810" has 52 pages devoted to it. Most of it is from primary sources.