I've found a lot of use with the 'Inverse Scrolling For Normal Mice Only' - However it only inverses the vertical scroll wheel, and I'd really like it to invert the horizontal scroll wheel on my mouse as well.
It's only a small thing, but it'd be really nice to have.
I would also love this. I use a Logitech MX Master 3 mouse, which has a separate horizontal scroll wheel. I'm content with the behavior of the vertical scroll wheel (I leave the inverse setting off in BTT, but I have the system "scroll direction: natural" box unchecked). I want to invert the scroll direction of the horizontal wheel independently of the vertical one.
I've stopped using it in favor of BTT myself, but Scroll Reverser does allow this if you need it now: https://pilotmoon.com/scrollreverser/
This would be a fantastic addition!! I also have an MX Master mouse (3S) and got used to the "natural scrolling" behavior. However, it only works on the vertical axis, and I'd like to reverse it horizontally as well. It's very strange to have mixed scrolling directions like I am currently.
Hope it's not hard to implement! 
While Scrollreverser (thanks @shelshok !) is great, I'd like to keep the software running on my Mac to a minimum
I think I found a workaround, but it's not as smooth so having BTT's native support would be way better.
If you disable natural scrolling in System Settings, and then use BTT's inverse scrolling feature, it reverts both axes, meaning they'll both be "natural" instead of 1 and 1.
Hope this helps! 
It would be a dream to have the scrolling setting available as a conditionable toggle or just a simple action.
Then people could start to try things with Advanced Conditions to fine-tune their individual edge-cases:
If active_app_name = x | Natural scrolling enabled
If active_app_name = y | Inverse scrolling enabled
If fingers_touching_trackpad > 0 | Inverse scrolling enabled
If currently_pressed_mouse_buttons contain x | Natural scrolling enabled
I‘ll add that soon. When I last worked on scrolling features (~12 years ago) any logic that was run while scrolling did significantly impact the scrolling performance . However this doesn’t seem to be the case on modern systems anymore, I tested some conditions and even scripts and couldn’t see big performance issues anymore.
If you need any tests that I can run on my end, logs, etc., please ping me and I'd be happy to help
The workaround I detailed above is less smooth for some reason, so I guess it's better to stick with MacOS's scrolling direction selection. But you'll know better for sure