First of all I owe you an apology, you don’t seem to be the type of person that usually writes posts like “This is why people don’t use Linux: it doesn’t do everything exactly the same as Windows”, and my response might have been overly harsh from past experiences.
I understand it wasn’t your intention to say that, but that’s quite literally what people understand when you say “I tried to do X the Windows way and it didn’t worked”. And this is kind of what people are trying to get you to see, it’s not that the file manager has or doesn’t have that feature (which BTW I would also expect it to work, and I checked on my computer and it does in fact work so I’m not sure why you couldn’t select things from the search result and drag it someplace else), the thing is that you went about this with the thought “this is how I would do it in Windows”, and refused to accept that people who use Linux would look at this in a different light, i.e. think about how to modify things in place instead on how to move everything to a single folder. In other words what you WANTED to do was convert all images inside cbz and CBR files to webp, so instead of asking yourself how do I run this on all of these subfolders you asked how do I move all of these files into a single folder, and that’s the Windows mentality creeping out, you shouldn’t need to move things around.
Yes, Mylar will rearrange the things, but here’s the thing, if you had gone with the Linux mentality you would have learned how to run things in folders in place, which would have allowed you to convert the cbr to cbz in place, and then convert the images on those cbzs also in place, without needing to rely on the script supporting either CBR or recursion in the folders nor on Mylar to rearrange things. Also, just thinking about this, how would you have done it? Move CBR to black hole folder, then get them imported as cbz, then move all cbz to a different folder, then run the script, then move everything from that folder into the black hole folder and hope that Mylar doesn’t decide “I already have that comic, delete the one in the black hole since it’s lesser quality than what I already have stored”. Instead of just running the script in the terminal passing the root comic folder, do you REALLY think that your way is simpler?.
I understand the wildcards not working being confusing, and if you hadn’t mentioned that the documentation doesn’t mention it I would be in 100% agreement with you that it is confusing. My point is that the docs don’t need to mention features they don’t support, my counter example was regular expressions which are a lot more powerful than wildcards yet almost no search bar uses, and their documentation doesn’t mention it.
The message you suggested is a nice idea, if the search returns empty that would be a nice message that would direct people to the fact that it doesn’t support wildcards, I would encourage you to suggest it on the git repo or proper channel to the developers, or if you’re inclined to write code write it yourself and open a PR, this seems like a nice message that’s very informative and would improve the quality of the software.