IME yes, inaccurate. I have previously compiled OpenWRT for a wide range of devices from manufacturers with no official support and spotty community coverage so it's not like I'm not used to things like this. There's some talk about the issues with the E750 drivers/firmware on the openwrt forums or mailing list IIRC.
This should give an idea of how much much attention they pay to security updates and the response one can expect when opening issues or PRs on their repos:
[1] https://github.com/gl-inet/openwrt#product-branch-relationsh...