Admiration for you who have mastered the quote function… me, not so much 
In all my years, I have observed various conventions around audio file naming, some best practices that turn out to be situational, but never an actual standard. Perhaps there are best practices or standards in the realm of this or that app, or this or that discipline, but nothing universal.
The available options to embed in a filename include: album, year, artist, track name, track number, track duration, composer, featured performer, genre, sub-genre, label, etc. And there are all manner of “right ways” to order these, which to include/exclude, punctuation, etc.
In my mind, for these tools, it seems the only real solution would be to provide a means to specify a template for the Audacity label text.
Similarly, to include the path in FILE or not, that is the question. Personally, I prefer the path. Others, only the filename. Again, this is highly dependent on the user and their needs, so it should probably be an option as well.
Top level (or, as it actually works, first) performer and title values being used as defaults when missing elsewhere? Again, an option. It works for me and what I was doing, but not for others and what they might be doing. My current thinking is, this is another option (leave as-is, or use template) and for the second option have a template.
That’s three or maybe four more options, plus resolving any interactions with what’s currently in place. If you code, you know complexity growth is closer to exponential than linear.
I’m not really interested (at least, not at this time) in fleshing out the web interface to provide cookies and file transfers and so forth. That is, in part, because if I needed to do batch processing then I would use a macro tool to automate the grunt work. If using Windows, then something TinyTask, but there are [insert money here] more elegant solutions, too.
For example, if I were doing a large project using either of the web tools, I would open the editor and website, then automate the following:
- export file
- switch to editor
- open file
- select all + cut
- switch to web tool
- insert REM options
- paste clipboard
- click convert
- select all + cut
- click start over
- switch to editor
- select all + paste
- save file
Ideal? No. Better than manually doing those steps each time? Yes.
If your macro tool supports capturing variables, then the first step would be to prompt for “what’s the file name?” With that in a variable, the export file, open file, save file steps wouldn’t even require a pause for keyboard input.
Anyway, just a suggestion on how one might get some relief now rather than later.
I think I’ll spend a little more time making some REM options and templates. REM is ignored in the CUE standard. And while REM is non-standard for label files, it is also never seen by Audacity – the REMs are added post-export / pre-convert.
The web UI/UX is just a front-end to the actual tools. I never envisioned it being the tool for doing batch conversions. It accepts text and feeds it to the back-end tool, then waits for results and presents them to the user. That is why there are no options at all in the web interface, why it’s a “one file” tool, and one reason (of several) why it’s easier (on me!) to add controls by adding REMs to the input.
Bottom line: I’m more interested in providing the conversion functionality than improving the site UX. Honestly, that’s because I’m not using either tool anymore, so I’m not personally feeling the pain. It is also because, if I needed to do a batch conversion, I would do it on Linux (actual or via WSL) from the shell and use the tool(s) directly. Yes, I know, maybe I should consider releasing the actual tools… 