Not sure if this is for LMMS, Keystone Classic devs, or M-Au

Having trouble with LMMS? Ask about it here.
I'm really at a loss as to who to start asking here, so I'm asking folks I know are helpful and if it's not LMMS, can hopefully point me in the right direction.

First, the simple configuration.
MIDI Controllwer: M-AUDIO HAMMER 88 88 key fully weighted hammer action controller
LMMS running on an IdeaPad L-340 Gaming laptop (no memory or drive speed issues!)
Keystone Classic configured as the Steinway Grand Piano, default settings.

Oh, and a tuner app on my Android cellphone as of last night. This concerns only notes below A1 (A1 is fine). As you move to deeper and deeper notes, they get farther and farther out of tune, with G1 almost being in tune with G2, and C1 registering as something fluctuating between D1 and E1 and severely out of tune with itself (sounds like two notes that are a semitone apart being played together).

I've heard this in other VST instruments that can play at that low pitch, as well.. But then, the keyboard is just a MIDI controller, not actually making the sound, right? Or is it? Could it be sending bad information for those notes? Or could it be something about how LMMS handles that end of the range? Or are several VST instrument plugins just wrong?

So here's my REAL, ultimate question: What do I do to diagnose and fix this? I realize not much uses that low end, but i;d still prefer that it be as well in-tune as the upper end is, and in tune with the upper end for the same notes except for the octaves. Is there are way, within LMMS, to tune each note individually by adjusting MIDI settings for each note? Or perhaps some kind of external work sound Audacity?

Does this also happen if you use one one of the build in synths?

Or maybe Synth1 ?

Your midi controller only send midi data, which LMMS can record. It does not make sound.
I wish I'd thought of checking that.... No, with the built-in organ, C1 is in tune, as is everything down to A0. I didn't test it with the tuner, though, because none of the tuners I found were accurate at those pitches. But my ears can tell if a note is the slightest bit sharp or flat.

So it's not spurious signals from the keyboard (and yes, I knew that was a long-shot, but if somehow it was programmed to send the wrong data for those keys, maybe...I'm new with this MIDI stuff).

So where do we go from here?
One more test I should have thought of to confirm that the keyboard was sending the right data at the low end...the piano roll. And it is. Keyboard is now, eliminated from suspicion of being badly programmed at that end (as I expected, but wanted to rule out human error in its programming)

So is it just bad samples in every piano VST I've found that works (again, the error is limited to notes below A1)? And if so, is there a way in LMMS to adjust the pitch on those? Right now,A0 is the closest to being in tune as C1 and in tune with C2 and above ... that's how bad this is.
I have noticed that most VST often have a limited range were they sound really good.

For piano I mostly use 4front piano. Good enough to make house.
And with that one, it's the same old problem as before: won't load an instrument. I did listen to the demo, though---was carefully listening for any even slightly out of tune notes...only heard one, right before it switched to the electric piano, and that one note made me cringe. But it's irrelevant in this case, since I can't get it to load. It also sounded really good for an upright.

Btw, in case anyone is wondering, I have family in town right now, so I'm gone again tomorrow and Saturday from about 1000 (give or take an hour) to around 1830. And when I tried to login today from my tablet, it wouldn't let me.
So, just asking again, is there a way within LMMS (perhaps a plugin, etc.) to tune those notes that are several semitones out of tune? I've read about auto-tune plugins for some DAWs, but is there one for LMMS? Thanks.
No specific autotuning as such. However, AudioFileProcessor speeds up/slows down any (audio) input until it's the pitch you want, if necessary- as long as you're okay with the note sounding shorter or longer than usual and more abnormal the further you go from the original pitch. But this is only for audio, if you sample whatever's going off, and correct it to the right pitch.
There is the pitch fine-tuning knob, that lets you change exactly how many cents off a note is. I suppose it would be possible to do some complicated sort of automation to keep it to the pitches you want it at.
There is no actual pitch autotuning in LMMS, in the conventional sense.
Ok, well I guess if I ever need that range (only one piece I know of that goes there---Rachmaninoff's 3rd Piano Concerto), I'll worry about it then.