It'd be great if Fedocal could support more flexible time periods than just: every N {day,week,month}. For example,

Nth {dayname} every {N} {month,year}

I cannot think of any other pattern. Perhaps you could suggest more useful patterns.

Backend implementation wise, it'd be parsing some strings with some regex pattern. However, it will be a challenge, in terms of UI, how to show it. May be we can replace, select input with a datalist input and have some validation around that.