OK, this is a huge ask, and I realise I'm dreaming, but... nothing ventured.
The Twiddler tutor is a bit of a wasted opportunity. The interface, with the Twiddler graphic and the fingering highlighted, should be extremely useful in teaching fingering... but it only shows the default config! So if you are using a variant configuration, not only is its guidance not correct, it's actively confusing.
In ascending order of desirability, could I suggest the implementation of one or more the following, to greatly improve the usefulness of the tutor.
3) An option to turn off the fingering highlighting on the Twiddler graphic on-screen.
2) An option to cross-refer the config file you're using with the tutor, and have the on-screen Twiddler graphic highlight the right keys for your config. This would be unbelievably helpful.
1) This is pie-in-the-sky stuff, but... an option, when using a config with bigrams or other MCCs, to have the tutor detect the relevant letter combinations in the words it shows and penalise the typing of those words with individual letters when there's an MCC which could be used.
This last idea would be a total game-changer to get into muscle-memory the shortcut-using typing that @AlexBravo has been talking about. For example, I'm using an MCC for 'are'. If, say, the word 'care' comes up, I try to remember to type 'c' + 'are', but sometimes, especially, ironically, if I'm typing well, I just automatically type 'c' + 'a' + 'r' + 'e', because my fingers know individual letters better. And if I don't remember to go back and fix that, I'll never get the 'are' really embedded in muscle memory.
Failing option 1), even option 2) would be very helpful.
edit: Forgot to say (while I'm shooting for the moon, might as well aim for stars too), as someone who works offline a lot of the time, it would be very helpful if an improved typing tutor with 2) or 1) (above) integrated could be downloaded, to run offline, along the lines of the twidor.jar.
Thanks for considering.