What you do with the 220 Speer depends greatly on how it is loaded.
Now, first, let me say I haven't shot a black bear with these, so my definitions have to do with relative performance, and what I've observed on results with other game.
Someplace I've mentioned that if I was limited to using the 220 Speer at 1900 fps, where the manuals load it, I would suggest some other bullet, specifically the 200 Core - Lokt RN. More about that later, so bear with me.
First, let's nail a few things down that explain the bullet performance you received on the black bear you shot. The 200 grain Remington pointed bullet was designed for expansion at higher velocity in bigger cartridges, and the bullets you fired were likely on the low side of the expansion threshold upon impact. Nonexpanding bullets may tumble and lose their jacket - and I believe none of the pointed 200's (being more popular and bigger sellers in the high velocity .35's) have the true "Core-Lokt" feature, which is a thickened jacket midsection that prevents core slippage. The roundnose 200's do. Why? The Core - Lokt feature was discontinued in the pointed designs in many calibers due to budget cost cutting. Why? The dies wore out, likely, and were not replaced. The almighty dollar again. The RN dies are still marching on due to lower sales volume. Maybe the .35 Remington cartridge garnered a little extra attention from Remington since their name is on the case, as well.
The 200 RN Core-Lokt is tailor made for the .35 Remington, having the core retaining thick jacket midsection, as well as scallops and slits at the base of the scallops to provide expansion at nearly any practicable velocity. Never a bad choice.
Now, back to your pointy 200's. I'm guessing, but one of the bullets likely expanded a little, tumbled, and in going backward the larger diameter lead core snagged on tissue and was braked, allowing the jacket to slip off. Some may have tumbled without expanding, explaining their near perfect condition. Regardless, tissue damage may not have been all it could be. 38.5 of 4064, while no doubt a load that may work fine, probably didn't give the bullets what they needed in terms of speed.
Now, it's easy to relate lack of expansion to your problems with dropping the bear, but that very much has to do with what the first bullet fired did, and what it hit. If, say, the first bullet sailed through ribs and lungs on the first shot, it may well have not expanded - low threshold of expansion bullet, not much resistance. Subsequent shots at an energized, departing bear may have found his adrenaline up, and coursed through his body from odd (rear?) angles, hitting different things on the way. This may explain why some expanded (hit more resistance -solid muscle, paunch, bones) and some did not. You'd have to recreate where you found the bullets and entry holes to determine which bullet hit what, and in what order. Thus the variance in bullet performance - the tissue resistance is variable.
Now, would the 220 Speer have worked better? At Buffalo Bore or +P velocities, likely yes. A reasonable range shot (from your stand, perhaps? You did say 20 to 50 yards, very reasonable for the Speer) would likely have resulted in better expansion, more torn vital tissue, and the bear going down after running off a short distance - just what you want and expect.
A large black bear is one of the few animals where the 220 Speer can be reasonably put to work. For deer it is unneeded, and the Remington 200 Rn is likely better there, but it will work fine as I have proved to myself on whitetails.
I understand, but do not know for sure, that black bear muscle is dense stuff. Here the 220 Speer may be in its element due to the increased resistance. Should you wish to give it a try, I would recommend, at a minimum, using Hodgdon's good data with H4895 to obtain at least 2000+ fps, which is in the range of quite reasonable for any 35 Remington. For sound rifles with tight headspace, with brass well and correctly formed to the chamber, this can be exceeded somewhat.
Being that you are a handloader, I would not shell out the money for Buffalo Bore's stuff - I would make it myself (or yourself). IMR 4064 can work here as well, but you must be fine with powder compression. The amount needed may give you pause, and if it bothers you the shorter more compact H4895 will reduce this somewhat.
FWIW, this year I shot a big buck on the front of the left shoulder as he angled toward me at 30 yards. I recovered the bullet in the right ham. The bullet was the 200 Remington Core Lokt roundnose.
If you reread the bullet performance post, I mention that I found that the Speer 220 penetrated about 50-60 percent more than the proper Remington RN. Whether this is really needed on an unobstructed vital area shot is open to question. If, for whatever reason you must shoot the southwest end of a northbound bear the extra penetration may be helpful, but I find a well placed bullet in the chest is always the first shot to take and will wait for it. The Remington bullet dumps somewhat more energy near the entrance hole than the Speer.
So, what you choose depends upon how you'll shoot. Wait for a clear angle for the vitals? The Remington 200 RN is all that is needed.
If you think you might try a less favorable angle, I myself would only do so as a second choice and wait out the vital area exposure. If you are determined to navigate more bear going toward the vitals the Speer may have an edge.
But not shot too slow! That is my gripe with some of the published loads in the 1850 fps range - they're useless!