I work at a summer camp, and assist with the medical prep and
treatment (WFR).

I would definitely add a "Treatment Log". Record every treatment, no
matter how minor, in writing. No one wants to go to court, and this
may keep you out of it. I would place the log (Could be a simple note
book or binder) on the very top, so as to remind the user (you?) that
if you open the kit you should make a entry.

Other suggestions are good, obviously. Wilderness Medical Associates
did their test for wound irrigation with a 60cc syringe with an
18gauge tip. Or so I remember my instructor saying.

Ditch the microsheild in favor of a real CPR mask IMHO.

Add more band aids. That is what I always run out of at camp.

Perhaps some more tools for splinter extraction? Safety Pins?

I strongly second the idea of a contents list, especially if this is
to be used on more than one trip. Best suggestion on FAKs ever, IMO.