You'd be better off removing the tape and then overtopping that with the varnish .

Let that cure fully and then mask off the upper portion .

The one thing you want to avoid is a heavy depth of resin ( paint ) at that waterline . Varnishing over the top color and across that border between the colors will prevent that .

With the tape out of the way you will be able to easily ascertain the surface continuity , i.e. no ridge .

Light coats on the lower portion to avoid bleed over and again building too much paint thickness .