2013 Prius V Two Accumulator Leak Malfunction, Other Errors

My family are on vacation and solid Brake / ABS / Slip Indicator and ECB lights came on. The whirring sound (I think from the brake assist) is coming on every 4 - 5 seconds when the car is running. Brakes are working but seem different / looser. I don't know much, but I've spent a couple hours on this forum tonight and learned how to pull and look up the diagnostic codes. The codes that don't point to other codes are :

ECB - 69 - Accumulator Leak Malfunction
ABS - 33 - Rear Speed Sensor RH Circuit
ABS - 38 - Foreign Object is Attached on Tip of Rear Speed Sensor RH

I've seen some folks here that have needed to replace brake booster and master cylinder ($$), and I see that as a possible outcome in the Toyota repair guide for all three errors. However, I had also driven through two deep puddles, shortly before and did read that one guy thought he might have gotten some gunk in rarely-used slip control / ABS valves?

We're a long way from home on a car trip. Nearest Toyota dealer is an hour away. And I just dropped $1,800 on a water pump and some other work before we left.~180k miles on the vehicle, all from us; regular maintenance performed.

I'm not a guy with car mechanic skills. I could use some advice before we start making moves first thing on Monday morning. Is there a procedure where a regular auto shop could test / flush those valves to see if it's something lodged? Is the car safe to drive (I assume not)?

THANKS