Phanx is listed as the current maintainer of Grid, and the last update was on May 11, 2018. That was only four months ago. She can more easily be reached by sending her a message on Wowinterface. This is her user page over there. If she is wiling to accept your updates, or even take over Grid, then click the Report Project link and follow the prompts. Provide all the information possible about your attempts to talk to Phanx, permissions or not to take over the addon, and whatever else is appropriate when you report it.
Then a Curseforge file moderator will look into the situation and take it from there.