I'm curious if the Luftwaffe recently held its first Veterans Day celebration this month
a) The first actual Veteran's Day will be held in 2025. There was a smallish reception held by political parties in the Federal Parliament to mark the occasion this year.
b) Under German definition of "Veteran" for this event any soldier who is serving or has honorably served in the Bundeswehr is considered a veteran (and before someone asks, yes, this excludes Wehrmacht soldiers and NVA soldiers who did not serve in the Bundeswehr). That's about 10 million people, of which half a million have served on missions outside Germany. This - external - wide-reaching definition is due to the Bundeswehr, the Ministry of Defense, the German Soldiers' Association and the German Reservist Association being unable to find a common definition for over five years.
c) There will not be any honoring or other activities specifically towards any "section" of veterans or any historical timeframe in the context of this "Veteran's Day" event, nor will there be any assessment or appraisement of such historical timeframes or the action of veterans during those. The (sole) purpose of the event is raising awareness to the continued existance of people who have served the country and its population in its armed forces, no matter in which way. Germany's "Veteran's Day" is broadly comparable to the "Armed Forces Day" of other countries.
d) The event is not intended as a celebration
by the Bundeswehr and its soldiers, but
for the Bundeswehr and its soldiers. Sorta. In reality none of the related organizations really have much of an idea "how" to celebrate it or "what" to celebrate. The date, June 15th, was chosen pretty much at random and refers to June 15th 2019 when the "Veteran's Badge" was first handed out. That "Veteran's Badge" itself is largely ignored by existing veterans btw, less than 1% of those eligible to get one applied for it.