All do-it-all-for-me platforms are limited by the programmer and source data and, most importantly, the fact they are programs in the first place.

I think the tenants just may not know how to operate the system or thermostat or something...

Theoretically, the insured high-ratio mortgage is only available to you while you reside in the property (it is a home ownership programme); if you the property is no longer your primary residence, then you should bring your equity position to 20%.  

tl;dr: The thermostat broke, I fixed it. 

She has been a computer programmer her whole adult life. 

Guests often look for those.Have also seen a recent study that says that 82% of guest prefer to stay in smart home enabled properties and that 60% are willing to pay more to stay at those so I'd recommend adding smart home devices (locks, thermostats, Roku TVs) and clearly market those in your listings.

Should I install additional thermostat on the renting unit and better separate the meters.

I didn't replace the thermostat, because it was only about a year old at the time... and it failed last week, requiring a Saturday-night trip to replace it.The bathroom had been redone in the past couple of years, so I mostly left it alone. 

You can use a vacuum against the outside to get a little bit of dirt, leaves, bugs, etc out of it, which will help some.If it has a cord and plug - it's not hard-wired - crank down the thermostat so it comes on and stays on for a while. 

Currently the thermostat/utilities all go under unit A but I am going to price out installing a new meter for unit B and getting them on a separate utility plan..