A bit too general.
In fact, hand padded chest gives more flexibility to the structure. In other words, a hand padded chest can be both soft and hard based on the coat-maker's working.
I think Grand may be a better choice than Lai if you like "hard" bristish style.
Actually, the machine sewn canvas is harder than hand padded, so I don't think it is the cause of your suit problem.
I think it look more like the canvas and the front cut has a little "mismatch" it make the front can't stay flat.
A bit too general.
In fact, hand padded chest gives more flexibility to the structure. In other words, a hand padded chest can be both soft and hard based on the coat-maker's working.