I worry that the lack of responsiveness may be related to the overall scope of Grin++, which is both a wallet and a node. That’s quite a footprint for a single piece of software, and it may be the cause of reticence from the Davids considering their previous development work resulted in them becoming essentially the helpdesk for many often angry users. Some may recall that the unification of wallet and node in Bitcoin was part of the inspiration for Monero to split those altogether, making operations much simpler and later inspiring Grin to do the same.
If Grin++ as a wallet winds up as abandonware, it may be worthwhile to consider a new proposal to fork it and split the node functionality out such that it can be run as standalone software. We have an even more user-friendly if less configurable (for now) wallet with Grim, but maintaining multiple node implementations is both a rarity and a serious strength for a project like this (which already paid off once before). Redefining the scope like this may encourage someone to pick up the PIBD implementation and ensure the robustness of the network going forward, since ultimately if the wallet is unusable then Grin++ is at risk of dying off over time anyway.