These are great suggestions! I may work on this over the holidays...
I should point out that, although the "hint" shows *an* alg for a given case, you're free to use whatever alg you know. For example, for the simple CMLL H case with vertical "columns" it shows R U2 R' U' R U R' U' R U' R', but when the columns are horizontal I use R U R' U R U' R' U R U2' R' and avoid the AUF. The tool doesn't care. In fact, you're free to make mistakes and undo them during the alg. All that maters is that you arrive at a "solved" state (which in the case of CMLLs means oriented & permuted top corners [with first two Roux blocks maintained]).
On the other hand, you're right, being able to add your own algs would be excellent. I may do it in the form of some general community contribution mechanism and/or some locally stored personal custom set. I think, for now, I want to avoid profiles and logins and a central database, etc. Right now, all your preferences and selected algs are just in local storage.
Technically, it's not that difficult to allow custom algs. It's literally all driven by
this single file. The catch is that baked into the code is knowledge of various scrambling strategies and the meaning of "solved" for each set (e.g. CMLL scrambles the M slice while COLL doesn't and "solved" means CO + either F2L or F2B maintained). Also the kind of diagrams to show (e.g. top face only or top/front as in EO and L4E sets... and I'll be adding a 3/4 view [top/front/right] for F2L/SB cases soon). So anyway, I'll need to make all of that driven by the data as well and provide a user-friendly way of submitting.
For a less user-friendly way, it *is* all open source:
https://github.com/AshleyF/briefcubing
Have fun!