I am really not that much of a stickler with finishes. I am more of a "form follows function" type. I could not make a living wood working from where I am at, initially. I just have the time, and perseverance, to keep sneaking up on that cut line until it fits, just so. I do have many years of machinery and power/hand tool experience. But, I was doing this stuff when I was 8, before I had anything beyond a dull saw and a hammer. That's been the biggest difference, really. Quality tools.
Here's a really neat trick for seams. I use fine line (Although the frog tape would suffice.) tape, on both the cabinet and the baffle, creating a 3/8" wide stripe. Then I mix 5 min (have to work fast) epoxy with cabosil (baking flower would work as well) into peanut butter consistency and fill the stripe, and then carefully remove the tape immediately. Makes a factory type looking transition, or a subtle ogee effect. Especially handy if the veneer has made the cabinet (pre-cut, flat pack?) larger than the supplied baffle.
After paint.
This would have to be done ahead of the textured surface, though, or else when you tried to wipe the filler tight with the putty knife, the texture would telegraph ripples into the stripe. Otherwise, would have to sand the edge smooth first, where the knife was going to travel on it.