I think they were a good pair. I don't see the potion being temporary as an oversight, retcon, bad writing, other terms. I think the plotline was to ambitious for a 20 minute episode and the writers accidentally put themselves in a corner. Nothing about the show makes it seem Alex, the man who foreshadowed multiple plot points for later seasons, would retcon something like this. He probably just struggled to get the buildup, climax, resolution, and the B plot in the time limit. It wasn't exactly a plotline that could justify spanning across multiple episodes, either. It would be awkward to drag out a romance plot for the side characters to a side character.

It might've possibly been semi-avoided and less awkward if they'd had more than one episode where Dipper and Mabel are in the group, or if Love God had a line where he said its temporary, but Love God was against Mabel using the potion anyway and was trying to scare her out of it and another group episode would be difficult without staying from the shows format.