The jacket is perfectly alright, if a trifle long by present-day standards. Kilt jackets seem to have become shorter after WWI, quite possibly due to a shortage of material after the war. If, at some point n the future, you decide you would like it a tad shorter it will be no big deal to whack an inch or two off the skirt with the end result still looking better than many an altered tweed sports coat.

Wear it a few times, and then decide what to do.