You can use their online web-editor (similar to OverLeaf for LaTeX) or download the open-source engine and run it locally (there are extensions available for many text editors).
Compared to LaTeX I find it much more comfortable to work with. It comes with sane, modern defaults and doesn’t need any plugins just to generate a (localized) bibliography or include links.
Since Typst is very young compared to LaTeX I’m sure that there are numerous docs / workflows that can’t be reproduced at the moment but if you don’t need some special feature I’d recommend giving it a shot.
The main reason for splitting up the relays into two sets is that with 10A traces the connector pins would violate minimum separation distances. I would have to get even larger connectors. The ones in the design have 5 mm pitch.
I’m assuming the original board also did this for the same reason although their board is set up for 8 motors split into sets of 4.
I’ve also had some trouble sourcing a 10A fuse suited for inductive loads but I’m sure I could find one with some more time.
The whole board is on its own house circuit fused with a 16A breaker.