Specific to your case
First of all I think your assumption is wrong. When the app states:
~91% battery. 460ma current consumption with regular use(full
brightness). 3:40 hours time left(avg last 5 minutes).
This rather means you have 91% capacity left, or in your case 3731mAh from 4100mAh. It's currently drawing 460mA with regular use having screen on full brightness. And based on the average of the last 5 minutes you have 3:40 hours left.
So the 3:40 hours is not linked to the 460mA the way I read this information.
I didn't go through it but this user guide from the authors might give you more insight.
I have no experience with that app but first of all you'd want to know how that app calculates these numbers. The app doesn't look like open source so reverse engineering it or contacting them seems like valid options.
The time left on these apps are always an indication based on what you did up to that time (and often starting from the time you stopped charging the phone). Nothing more than a prediction. If you use the phone more/less for the next hours it won't match reality for sure.
This app has some ratings in the store indicating there are bugs:
Martijn Kösters 5 januari 2017 Starting app Has to be done manually
after fully charging. Otherwise fine. Strange?
robert zegers 21 oktober 2016 Bug The widget keeps getting stuck on a
certain percentage.. I have to reboot my phone to fix it. Ive got a
See play store link for more.
If this intrigues you you could always do tests and see how accurate these numbers are. How long does it last you in real life? Are you having issues with battery life? If so try to find out what app causes it by using the Android battery statistics.