Well first of all matte paint is "flat" paint. Non washable. If anyone tells you it is don't believe them it's not. You need an eggshell or in BM pearl finish. (depends on the company for the name of the finish).

Ideally, the most washable paint for kitchens is a semi-gloss but I personally don't like the shiny finish.

I use BM pearl throughout my home and it washes like a dream.

I've used the SW washable paint in white. It was flat, and yes, it did indeed wash up nicely. This was when my kids were little, too. They used to like to lay on the sofa and put their dirty feet up on my wall, and I recall more than one bowl of food being dropped near a wall, splattering and yes, it came up, even though it sat there all day.

I'm likely doing the same in my new kitchen, painted backsplash so I can spend more $$ on appliances. You could always use the flat on the other areas, and the semi gloss just in the backsplash area.
What I always do before I even start painting is to put a bit of the paint in a tupperware type bowl with a good tight lid, label it, and keep it in the utility room. That way, it's no big deal to do touch up just in case.

The Aura paint from BM IS scrubbable in a matte finish. In fact, it is one of their biggest advertising points. I have it on my backsplash for 2 years plus and it is completely scrubbable. I wipe down my main prep area every week or so without any change in the paint.

I use the matte Aura paint exclusively now, even in my rental properties because of the way I can scrub down the walls and touch up areas without an obvious line between the new and old paint. I just patched 4 sq feet new drywall in my sunny dining room that was painted 18 months ago. I did 2 coats of the matte Aura over it. You cannot tell that I didn't paint the whole wall.

It is an amazing paint-worth every penny of its high price.

Thanks - I'd like to just repaint my backsplash for now, but don't want to really change gloss level since we have imperfections, will probably be doing some touchups (2 reasons I chose Matte to begin with), and really don't want an obvious mismatch in the corner (I have an end wall). If I have to put a piece of wood trim on either side of window, or paint the entire window wall in the Aura that's OK, but don't want to repaint entire kitchen/FR right now.

Will the Aura Matte match the Regal Matte?

The Aura paint is available in all BM shades so I would think that the colors would match. I think you would have to paint the whole wall though. Check with the guys at the BM store. They are usually pretty helpful. Wait till you try that paint-you might keep painting the rest of your house.

A few tips...Aura paint dries in less than an hour so you have to be careful with overrolling. I would do your cutting in, then wait an hour before rolling. Don't keep overrolling the same area. Repaint time is only an hour. Believe it or not, I did 2 coats in my entire kitchen in under 4 hours. Good luck!