• 9: slant, like the "s" in "Est"
  
• 4: several completely different letters like middle-word -g-, final -s.
  
• 0: tricky because it's more tidy, which doesn't mean different scribe. Still, I see differences in several letters like the various s-shapes.
  
• 7: again tricky since it's a different layout but I see differences in a number of letters, even small "e".
  
• 3: definitely different in a number of letters, though it might be a "quicker" hand
  

That leaves 1,2,5,6,8 as the same hand, although there are some differences between them. But that's my guess.

2, 6, 3, 5, 9

I've reorganzed the samples as follows:





Comments:

• I think samples 8 and 6 are the same handwriting.
  
• 2 is very similar to 8 and 6, probably the same handwriting.
  
• 3 is messy, perhaps it's note-taking, but also very similar to 2, 6, and 8 and may be the same handwriting
  
• 0 is formal handwriting, so it's a slightly different style, but it appears to be essentially the same letterforms, so it might be the same handwriting
  

The style of handwriting of 8 looks familiar. It was used in parts of France in the 10th century BUT these are clearly more recent adaptations, they are slightly less formal than early medieval script. They used this slightly less formal style of handwriting in the area around Rome in the 15th century. This style was also adapted by the humanists when they rejected the Gothic style.

After this, they look like different hands, but I have some comments on them...

• 5 is basically the same style as 8, 6, 2, and 3 but he writes the "a" and the "r" quite differently and the "c" has a flat top, so it's probably a different scribe even though it's the same style.
  
• 7 looks like a style used in parts of southern Lombardy but I'm not completely sure, some scribes traveled and picked up styles in different places.
  
• 1 is the same basic style as 8 and 6 but the scribe handles the pen differently, and varies the speed of the pen to create the thick and thin parts. It takes a bit of extra skill and coordination to do this.
  
• 4 is interesting. I think I recognize this style as well. It is a more classical style and resembles text I think I saw in a manuscript from Bologna (or somewhere around there, I can't remember exactly).
  
• 9 is stylistically similar to the first ones, but... it's a quick hand and much more connected than the others, a cursive hand. If it turned out to be later than the others (or a letter-writing hand rather than a scribal hand), I wouldn't be surprised. It can sometimes be difficult to tell if a cursive hand is the same hand as someone who also does calligraphy, because the slant, letterforms, and thick/thin balance of cursive styles and calligraphic styles are quite different even if it's the same scribe, but I'm fairly sure this is a different hand.
  
  

Case 0 looks like a humanist hand, while all others more look like some form of gothic.
This made me think of Sozomeno, but I did not look back.
And it did not help me.

The first I would eliminate would be Case 4, because it is ruled, and has a different letter height to line spacing ratio.

After that, I could find reasons to throw out almost all of the other ones, so I gave up.