Everythings seems to work fine with automatic or custom(75%) scaling.
At 100% scaling "Read" "Clear" "Verticle" "Diagonal" and "Statistics" buttons no longer function.
At higher scaling more buttons from the bottom of the UI stop working.

It looks like only the region covered by 75% scaling will take player inputs and anything beyond that will not, but higher scaling will make the UI larger than that region thus placing buttons out of input range. Desktop resolution is 1600x900 (didn't see a resolution option within Factorio?)

Thanks for the report. I reproduced it with 1920x1080 and 125% scaling.
I have reported it as a Factorio bug here: https://forums.factorio.com/viewtopic.php?f=7&t=67799 since i managed to create a very minimal mod to reproduce it and had a similar report from another mod.

For the time being you'll have to reduce your scaling before changing settings in FARL. If the bug turns out to take a while to fix i will change the gui slightly to try and avoid it.

Thanks for the response. Now that you have pointed it out I do see this behavior in other mods.

Mostly I just wanted something out there others can find about the scaling issue as I was setting up FARL for the first time and it took a while before I figured out what was going on and why I couldn't get it to read any type of custom blueprint (of course the bug took out exactly the buttons related to custom blueprints).