(sorry bad english)

Crafting speed perk is for manual crafting, automation machine, or both ?

manual only

Is there a cap to crafting speed in the game? I wanted to see how fast 1500% bonus crafting speed would be but it seemed like the crafting speed stopped increasing at a certain point.

Tbh. it feels like it stops pretty early since a crafting speed of 270% shouldn't reduce the crafting time of a 20s item to 13s.

Edit:

Just meassured the time and it didnt change the crafting time at all on 270%. I think there might be a bug.