About limits - Have you seen this FR
https://forum.arturia.com/index.php?topic=94403.0 ?
About ratcheting - You can't add more steps than 16 to the sequencer on the run. But as you can have notes to last up to 4 steps, then you do have some possibilities to get different note lengths. And you have the trigger probability parameter.
For some things you might only need to manipulate the sequencer rate.
You can for example use the sidechain, the modulation and the excisting trigger possibilities to simulate ratcheting allready.
The retrigger suggestion in this thread
https://forum.arturia.com/index.php?topic=93812.0 can add further possibilities.
But yes it would be easier (and more correct i guess) to be able to clockdivide (and modulate) the sequencers individuel steps and for that matter the Functions individuel steps directly.