Congratulations for this quick identification system.
I suggest a simple addition that would be helpful for identifying the watermark varieties (add in the "comments" column the watermark type 2XI, 2XII, 2YI and 2YII.
These watermarks are difficult to differentiate but the Michel catalogue mentions how the stamp curves according to the structure of the paper which is also directly related to the type of watermark.
It can be inserted in the preamble this :

It is a pity that one misses out on these watermark varieties with their big values:

A form notice can be added in the preamble:
2XI-minimum value
2XII-medium value (but not always)
2YI and 2YII -high value
2XI and 2XII watermarks are on stamps Mi#362 to 379, Mi#405 to 422, Mi#435 to 442, Mi#453 to 458,
2YI watermark is on stamps:Mi#367, 405, 406, 407, 409,410, 411, 412, 413, 414, 415, 416, 417, 418, 421, 435, 436, 437, 438, 439, 440, 442, 453, 455, 457.
2YII watermark is on stamps: Mi# 367, 415, 418