Vinegar is an effective form of carbon dosing like alcohol dosing or NOPOX, so it reduces nitrates and phosphates. This could be good or bad depending on where you are with nutrients.
Have you measured your pH at different times of day? Giving 1 number can be very misleading. My pH goes from about 8.15 to 8.30, with the max at about the end of the display lights being on in the evening and the min about the end of the dark period right before the lights come on in the morning. That is with my refugium counter-lighted (which should reduce the swing). This means my tank is about 50% more acidic in the early morning than in the early evening every day.
My point being that your pH value might be ok if it was measured just before your lights went off (max), but would be pretty worrisome if you measured it right before they came on in the morning (min).
If you don’t want/need to add acid then you will probably have to cut back on the kalk and add some balanced 2-part separately. I think that this is the typical experience, that unless you are using a calcium reactor (which lowers pH), kalk is unlikely to be a complete solution for Alk/Ca.