Alex,
XX Corps Artillery was in process of inactivation during early 1946, so HQ with only 6 pilots very well possible. Normal minimal allocation of L-type planes were 2 each for HQ Corps, HQ FA Brigade and Air Sections of the respective FA Battalions.
Pilots/observers were US Army. Planes maintained at USAAF level when field repairs were not possible.
Also see
https://xxcorps.org/documents/xx_Corps_Artillery.pdf
Regards,
Leendert