I know you are not wanting to muddy the topic with details of usage, but I do appreciate that you are willing to respond. It is integral to the discussion of "major fault" and warranty issues.
We sell on average just short of one Branson tractor per every working day, and the 3520H is the most popular model. I do not recall the last front axle issue. I am not saying the front axles are bomb proof, but they are good. I bet if we checked our shop records, we would find a warranty claim here and there over the years that relate to the front axle on some model of Branson, that is surely possible. But it is far from common.
It is essentially the same axle they use all the way up to the 5220R, which is 55HP. The 5220 is wider, but most parts are the same other than that. At the 35HP level, especially with an HST, you should not be breaking axles unless you are using the tractor outside of the design limitations of a compact tractor.
If you look at a construction grade loader tractor, like a JD210/310, Cat 426 etc., you will see they are designed to dig with the front bucket. The loader is made for it, and the front axle is made for it. A compact tractor is made to move and load material. Of course it needs to be able to dig into the pile a little and it should not be fragile, but it is not designed for digging actually. The issue is not so much weight on the front axle, it is the fact that the front end is designed to assist the rear axle, it is a MFWA tractor - mechanical front wheel assist. The cross sectional area of the rear axle shafts is almost 4 times larger than the front axles. When digging, the rear axle must do the pushing, or at least the lion's share of the pushing with the front axle assisting. Heavy rear ballast in the tires and a heavy box scraper or something hanging off the back will help the rear tires do the pushing. If you are digging and the back end is light and just barely contributing to the tractive effort, you are eventually going to bust a front axle shaft, and that applies to all brands of compact tractors. Our shop repairs all brands, and we have replaced axles shafts or front gears in about every brand over the years. Typically, although we try to say it nicely, it is abuse. Not intended abuse generally, more like a lack of knowledge abuse.
Might it be that you need a different type of tractor for your usage? Maybe a skid-steer? They can take a beating. Or maybe a full size TLB or skip loader? When digging heavy, if you ballast really heavy in the rear, you can probably cure your front axle issues, but then you find the next failure point. If you look at a typical Bobcat skid-steer, you will see that when the bucket is all the way down in the digging position, the loader arms rest against stops built into the main chassis frame. So when digging, the stresses are spread out and not all placed on the loader arms and not all on the pins. I have a Takeuchi TL130 track loader and it seems you just can't hurt it no matter how hard I dig, push, pull or lift. But the loader arms rest against the main frame when digging. If you really "heavy-up" the back of your Branson, then watch your loader arms, pins, mounts, etc. Put a wrench on them often, loose bolts are the start of all kinds of headaches if not kept in check.
We sincerely wish you well. It is nice that even though you must be very frustrated, that you are civil about the discussion.