Having given this some more thought, it appears to me the issue lies at a somewhat deeper level: you cannot search for a file - at all.
You can only search for a post that contains the (only) download link to a file. That is why the search options are what they are: forum-like, not file library-like. (Apologies if this has been mentioned before, in that case I overlooked.)
I did read the reasons given for the site update. Apart from the need to move to new software and account-related features and the likes, I understand the aim to give uploaders more control over their files. That is actually very uploader-friendly. BUT, the price that comes with it regarding finding what you're looking for, and so the success of sharing the file(s) itself, is in my opinion too high. There was an efficient and versatile file search engine for the huge and immensely popular freeware file archive and now it's gone.
I read a comment somewhere along the lines of "Uploaders will just have to come up with better file descriptions". While that sounds logical, I can see three problems with that:
Uploaders (creators in most cases!) "will have to" do that ONLY because it was decided to choose an indirect file access method to their work. Giving better control over one's creations online is great, but this mechanism is awkward. The downsides of it cannot be blamed on those that shared their creations for free, especially not if they did so (long) before this radical change was made.
Not all uploaders are still keeping track of their files, especially if they were made a long time ago. Part of them will even have left the flightsim world and heck, some of them even aren't alive anymore.
Even when the file description, and with it the title of the post that gives access to the file, is perfect, the search engine will not always find it. For instance, searching for "FS2004 Piper Tri-Pacer For AI" (with or without the quotes), in FS2004 or FS 2004 General Aviation or all files, does NOT find this post. (situation early August '23)
I think it would greatly help to include the file names (xxx.zip) to the posts in such a way that the search engine will find them.
This information is available in the system, as the download button with each post representing a file is pointing to the file in question. The url under the 'Download this file' button does not contain the file name, but the info is coupled in the system somewhere. I do not expect the whole new setup of this site to be reconsidered, but I hope this option will be considered.
Cheers,
Erik