Removing the old paint “edges”

I've never heard of "IE". That looks like a pretty important question. They placed the mix label directly over the original can label. Who knows what pertinent info that's covering up.
maybe the E in "IE" refers to enamel. If that were the case, it's been my experience that enamel has a hard "shell" with a soft underneath. If that is the case, then yeah, it wouldn't last long if it were wet sanded and buffed.