@chack has been working behind the scenes on the quirk and I think some good progress has been made as far as overcoming the error that happens during device pairing. Having the device present as a fan is something to do with the Zigbee SDK not having a fan cluster specifically for a switch like this. He has some more info here:
The answer I got about having multiple fans attached is that full speed in On/Off mode should work, but the other speeds wouldn’t because “A fan switch controls two fans, the speed is normal at high speed, but in the case of medium speed and low speed, the speed will be reduced by half, because the medium speed and low speed are regulated by capacitors, which has limited the output power; Similarly, if one fan switch controls more fans, the fan may not work.”
As mentioned above, there are a couple ways to change some of the config options that currently aren’t showing up as entities. There is also some info about that in the manual towards the bottom:
Blue Series Fan Switch • Setup Instructions • Home Assistant - ZHA | Articles | Inovelli | Intercom
@signbit for the WhisperGreen fans, one of our engineers pointed out that they are DC motors? He thinks that may be a problem, but I wasn’t aware that DC motors were a thing on exhaust fans. Is that a common thing?