Again, the file browser pane is just an interface, anything you do there has the same effect as if you have done it on your operating system file browser. If you want to recover your deleted files, search for help recovering files on MacOS, I can't give you any specific advice about that since I'm not a Mac user but at least for Windows there are a lot of recovery softwares out there on the internet.
As a note, what you are seen on that pane are not files that have been imported into RStudio, they are just files in your system, like you would see with any other file browser on any other program.