I'm not sure I'd ever describe a peach-coloured tie as 'subtle'. And I'm not sure what 'too subtle' would even mean in this context. The tie doesn't strike me as being particularly casual though, if you're going for a casual look then a more casual tie might be a good idea.
The outfit might look okay, providing the coat fits well; a different colour trouser that's less similar in colour to the coat might look better though.
The flatness can probably be remedied if they deconstruct the tie, press the fabric flat, then refold it, providing the crease that's been put in isn't too sharp. Not so sure about the shine though; there are ways to get shine out of fabric depending on the type of fabric but there's no guarantees. I would send them a pic and ask them what they can do.
The blue jacket looks great on you. Unfortunately I cannot say the same about the Isaia. Even if you could fix the fit the high button-stance and short stubby lapels are not a good look on you, the elongating effect of the long lapels on the blue coat looks infinitely better. If you must wear a high-buttoning coat it should probably be 3-button and fit must be impeccable.
Late September means it isn't too late to get something made to measure, then you can get whatever cuff/collar configuration you want.
And please don't wear a skinny tie. Ever. (Where skinny is anything 2" or narrower)