Jazakallah khair!
The work that you do and your persistence in archiving is always appreciated! If I could offer some thoughts about the Quran's preservation for future readers:
It is important to understand Allah's promise when it comes to the Quran:
[Quran 2:106] We do not abrogate a verse or cause it to be forgotten except that We bring forth [one] better than it or similar to it. Do you not know that Allah is over all things competent?
[Quran 15:9] Indeed, it is We who sent down "the Dhikr" and indeed, We will be its guardian.
The nonbeliever claims that this verse is referring to the bible. However, when looking at the context, there is no mention of the bible or the people of the book. The subject of these verses is the Quran (see 15:1 and 15:6 which uses "Dhikr" to refer to the message the prophet Muhammad received). And this is Allah's message that indeed he will personally guard this Dhikr the prophet Muhammad received.
[Quran 75:16] Do not hasten your tongue [O Muhammad], to hasten with recitation of the Qur'an.
[Quran 75:17] Indeed, upon Us is its collection and its recitation.
This verse is Allah telling the prophet Muhammad do not worry about the Qur'an, ALLAH HIMSELF will personally collect it and recite it. This is Allah's promise that he himself will personally collect the Quran and recite it. So Allah promised he would collect the Quran and ensure it is recited the way he wants it to be. Allah had an influence in the Quran after the prophet Muhammad just as he promised--and thus Allah is the one who will compile the Quran and put it together. Allah, as he promised, ultimately ensured the Quran we have today is the one he wanted us to have, just as he promised and just as he promised he would protect it (15:9). And in 2:106, Allah said he has the option to abrogate or cause a verse to be forgotten...
So no, the "history" doesn't matter. Allah said he himself would ensure the Quran, it's compilation and its preservation. So in the end, ultimately, regardless of the history or instances of human error, Allah is the one who compiled the protected the Quran in the form we have today. Allah's intervention was in place to compile the Quran we have today and have it recited the way it is. Thus the Quran we have today is one that was compiled and recited by Allah as he promised it would be, regardless of the errors of humans, in the end, through his complex interventions, Allah ultimately made the Quran the way he wanted it to be (the way it should be) and he will be its guardian. Done. End. Resolved.
Now, let's address the manuscripts: Those manuscript variations had to do with small spelling errors or different readings, nothing significant at all...
This is nothing new, and a deep level analysis of all this data will lead you to the conclusion the Quran is indeed preserved. You need to look at both sides of the argument and do your research. I trust that after your humble research, you will find it like me and many others that even with the manuscripts we have today, that indeed the Quran has been preserved.
^ and this manuscript talk is even assuming Allah did not (in the end) personally ensure the Quran's compilation, recitation and preservation...
Through human errors, Allah could've distinguished the correct Quran from the false Quran using the companions of the prophet and other scholars at the time and influenced them and ensured they'd pick the correct Quran to recite and compile it the right way--and the in the end, Allah's interventions ultimately led to the Quran we have today being the correct one as he promised.
What I'm saying is, suppose in the future, we find a terrible manuscript (one that is NOT like the ones we have today--the ones we have today testify to the Quran's authenticity), but let's say we find really bad manuscripts with many errors and variations. Even amongst a sea of human errors, in the end Allah is the one who was responsible for the Quran's compilation, recitation and preservation--and ultimately ensured the final copy of the Quran is the right one he wanted. Allah did it, in the end. He distinguished the correct Quran from the errors and then allowed the correct Quran to be propagated. So even if that is the case that there are problematic manuscripts (and it's not the case) but EVEN IF it were the case, Allah personally made the correct Quran come out of all of this in the end through his complex interventions. As I said in my first post: Done. End. Resolved.
One may argue "but this makes the Quran unfalsifiable through manuscripts". And I agree. So stop trying to falsify it--it cannot be done through manuscripts (as they even admit).