I haven't gone through all the 40s and 60s Calker-scored Lantz cartoons to see if there's any of these old Zahler cues in there, but I honestly would like to think that a bunch of these tracks attributed to him might've actually been original compositions for the Zahler library (the "circus" tracks heard in such New 3 Stooges shorts as "A Flycycle Built for Two" and "Ready Jet Set Go" come to mind).
However, wouldn't surprise me if some of these are indeed recycled cues from old 40s Lantz scores, a few of these sound 40s-ish to me, like the "wah, waaaah" track you inquird about.