I would probably try to style it the same way through Editable prepare
I know it might be hard since there is a shortage of class / ID's to target and apply the style, but this is the most direct way.
You can also inspect the CB elements to see where is CSS drawn from.
Editable through BreezingForms is shown when you are using "Edit by type" option inside Content Builder.
Since that is the case, can you try to adjust the width of the element inside your form ?
Each element has "Size" input where you can adjust the width of the element.
Hopefully it will be reflected to you CB view integration.