Safe car seat cleaning help!

So my baby had an insane spit up/throw up morning while we were out today and she was in her Aton 2 car seat. I cleaned the seat up with baby wipes while we were out, but it needs a much more thorough cleaning. I have removed the cover and thrown it in the wash. Now for the straps and buckle parts. This is what the manual says:

Harness Straps
Sponge clean using warm water and mild soap. Air dry. Do not iron.
NEVER REMOVE Harness or Harness components from Infant Carrier.
NEVER USE bleach, household cleaners or solvents

Harness Buckle
Sponge clean or thoroughly rinse Harness Buckle with warm water. Test by
fastening and unfastening until an audible CLICK is heard after inserting
each buckle Tongue into the Buckle. If CLICKS are not heard, repeat the
cleaning procedure.
NEVER USE bleach, household cleaners or solvents.
DO NOT lubricate

Okay, so for my questions:

1. Is this saying that I cannot use anything except water on the harness buckle?
2. When it says "thoroughly rinse," does this mean it's okay to immerse it in water? There's puke way down into the buckle....As far as I can tell, the buckle itself is not removable, so unless it's okay to put the whole seat in the shower, I can't rinse it by running it under water.
3. What constitutes the "mild soap" that can be used on the harness straps? Does anyone have any product suggestions?

I've used a water & Dawn dish soap mixture to clean harness straps.

When I've talked to manufacturers about accepted mild soaps, Dawn and Dreft have been named, so those are OK. Just be sure not to saturate the harness with the detergent because you won't be able to get it all out.

As for the buckle, if you can't prop the seat upside down like on the corner of a kitchen counter so you can hold a cup of water over the buckle, then I'd call Cybex and ask them for guidance.

Just an FYI if you have to call Cybex.... Google for the number. The number on the bottom of my seat was for Regal Lager and they told me the are no longer the distributor for Cybex and could not answer my questions. I had to send an email and an answer took a couple of days. They said Cybex is starting to handle themselves now.

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An old tooth brush works great for getting stuff out of the crevices of the harness without soaking it. That along with a sponge and a quick rinse are what I've done in the past.