If you want to wear that particular sporran then do so.

However just so you know this "semi-dress" thing is really not helpful as it really ends up as too much for one event and not enough for another and that situation stands out a mile in neon lights for whichever guise it is used in. If it were me, and it is quite obvious that it is not, I would retire, permanently, the semi dress sporran and wear the black leather one for all events other than formal evening events. It does then, make your dressing options so much simpler.