On Windows at least, the standard is for the confirmation button to be on the left. For example closing Notepad with unsaved changes has the 'Save' button on the left:
Closing Chrome with unsaved changes also has the 'Leave' button on the left:
Creating a condition or action is a multi-step process like a "wizard" where you can imagine moving right through the process as you advance and left as you go back. In this case the buttons are positioned to correspond to that process. It looks like Windows wizards usually have a button ordering of Back / Next / Cancel rather than Cancel / Back / Next like Construct has. I suppose we could change it, but then we'll trip up everyone who has been used to the 'Next' button on the right for the past 10+ years, as even Construct 2 had the same button ordering. And then such fundamental UI changes mean things like documentation screenshots, lesson plans, printed books etc. all suddenly become out of date, and updating them all is a huge job that is basically never fully done, so then you have ongoing confusion with out-of-date documentation. So sometimes I think it is better not to change things like this, even if it's a bit inconsistent, as the cost of changing it may well be higher than the cost of leaving it as it is.