Yes, when I was cleaning these carbs on pretty much a daily basis, I found so many of those jet tubes cracked or virtually impossible to get reliably clean, I got in the habit of just replacing them. I kept a stock of them for the varying horsepower outboards I worked on because it was more cost effective for my customers to pay for the part than to pay for my time to "massage" on that little dude. I keep a new one on hand today in my spares kit for the BF20D I currrently own.
Those things being on backorder for the 9.9 doesn't surprise me because that outboard is probably the most sold outboard in Honda history. The D models are the best twin you can buy in my opinion. I have always called them "lifetime" models because that's how long they will last if well maintained.
The Keihin carbs on these though are a bit of a pain. Hard to clean and the so called "accelerator pump" is pretty much a joke. It doesn't work well when brand new, wears out VERY rapidly and most people can't even tell when the piston freezes in it's bore. I've removed the piston completely on several of them when parts weren't readily available and I never heard one complaint about performance.
BUT BOY! If that circuit gets plugged, it causes all kinds of problems! It's as if the carb can't "breathe" when the accelerator pump circuit gets dirty.
It's an area you need to pay particular attention to as you work on your carb. I can walk you through that as well as cover other "points of interest" so that you have the best chance of a one time and done job.
These carburetors are famous for guys taking them off 3,4,5,6, or more times to get them clean. They drove me nuts too when I first got "introduced" and I had been rebuilding automobile carburetors for years!
So, if you're "game" I'm willing to help you.