When using the drop down in the new conditions window, selecting Variables for example and pressing the first letter of some variable the expected behavior is to select all variables one by one, right? You can check in the video that this semi-works, it only always cycles only 2 variables and even this is not working always, as you see I'm pressing multiple times c or b but this not always cycle thru these 2 vars and the selecting stays on the already selected var
this is standard macOS behavior for such context menus, there is no way to influence this.
However there will soon be keyboard filter & navigation support for the right filter sidebar.
I was not aware that this is a standard macOS behavior. Thank you.
I've now done my research now and it turns out that by doing this macOS is allowing you to type whatever you search in that context menu and it will match it. I would have been great if this is shown somewhere, e.g. in the bottom right corner of the context. I've noticed that there's some "timeout", meaning if I wait X seconds it will "reset" what I have typed and I can start searching by typing.
Do you think this can be implemented as a mini floating menu or HUD to show what chars are typed and clear them after X seconds, which should be the real value after which macOS is clearing the typed text ? How to detect if such drop-down is opened?
I always hated this behavior since I started using macOS ~17 years ago 
Searching in MS Windows context menus is much nicer.
A mini hud or similar might be possible, however it would need to jump through quite some hoops to make it work nicely - I don't think I will add this for now. However I'll upload a build with the navigable sidebar:
I always hated this behavior since I started using macOS ~17 years ago
I'm using macOS for 3-4y now and I just expected to behave the same like in Windows and Linux, but I forgot that Apple always has their vision how things should work.
My question was more like is it even possible with the current BTT capabilities and not requesting you to implement it. Like I would imagine that the 1st step is to determine when such context menu is opened. If it requires too much explanation from your end or it won't work reliable at all with the current capabilities don't waste time on this.
Appreciate the navigable sidebar.