Thanks for the feedback I've been working on some improvements since you posted this.
It's now possible to access the keyboard layout for the tracker mode from the menu
Which gives the choice of two different keyboard layouts
As for how to play notes that aren't completely grid aligned, this requires using Effects, e.g to end a note mid way through a cell you would do something like this. 
There's a similar effect for Note Delay, which you would put at the same column as the note itself to delay playing that note for however many ticks you want.
The effects feature is also how you add Arpeggio, Portamento and a few other effects.
The software itself is based around the format used in hUGETracker so you can see the documentation for the different effects here https://superdisk.github.io/hUGETracker/hUGETracker/effect-reference.html
Hope this helps,
Chris