OK to clarify everything, here are the tests I did:

Existing tracks in one album = Missing tracks report.
1-12, 102-111 = 101
2-11, 103-111, 203,205 = 1, 101,102, 201,202,204
101,103,104,106-111, 202,205, 301-307, 504,505, 903 = 102,105,201,203,204,401,501-503,601,701,801,901,902

100 = 1-99
200 = 1, 101-199
500 = 1, 101, 201, 301, 401-499

I think it's pretty satisfying.

Now, in the FindTheMissing node, are listed all albums containing missing track(s). If it's a multi-CD album (with tracks 101,102,...,201,202,...) it will be listed in the node even if it don't contains missing tracks. That's the point.

Existing tracks in one album = Missing tracks report.
1-12, 102-111 = 101
2-11, 103-111, 203,205 = 1, 101,102, 201,202,204
101,103,104,106-111, 202,205, 301-307, 504,505, 903 = 102,105,201,203,204,401,501-503,601,701,801,901,902

100 = 1-99
200 = 1, 101-199
500 = 1, 101, 201, 301, 401-499

Yes it will work exactly as it should.
If there's no track# below 100 it will start comparing at 101.

It's working with an album containing
101, 102, 103, ..., 201, 202, 203, ..., 301, etc...

But as I said, I dont' know how to prevent such albums to be listed in the node if there's no missing track.

Dim list, itm, i,j,k, trackno, last, MissingSongs, offset

offset=0 '<<< Offset for multi-CD albums (100, 200, 300, ...)

'[Thank you Eyal] Calculate offset for tracks begining with > 100: <<<< Untested
If i=0 Then 'It's the first track of the album
If trackno = j + 100 Then 'Check if track# begins at 101
offset = offset + 100 'Adjust offset
j = j + 100
i = i + 100
End If
'Calculate offset for tracks begining with > 100:
ElseIf trackno > offset + 100 Then 'Track# changes range
offset = offset + 100 'Adjust offset
j = offset + 1
i = offset
End If