Issue: Category listing 'Cont.' while there is enough space in the first column

This is Working as Designed. The alphabetical groups are split with (Cont) whenever a column has grown to the maximum length, and this occurs within the boundaries of the alphabetical group (very common). It can happen with columns 5 long and groups 2 long almost as easily as 200 long with groups 50 long.

The category columns are designed to spread the entries as equally as possible across 3 columns, with the third column receiving a lower amount when there is a remainder. If the two entries from H are moved to column 1, then the entries are not spread evenly. In the category in question there are 16 entries. For an even distribution of entries across 3 columns, 16 / 3 ~ 6 entries per column. According to the algorithm, there is NOT enough space in column 1, because it already contains 6 entries. If two entries were taken from column 2 and put in column 1, then we have a distribution of 8, 6, 2, which is uneven and visually unappealing. The correct distribution is 6, 6, 4, which is used by your category.

This is the same column-splitting algorithm that was used by VaultWiki 3, although in VaultWiki 3 the minimum entries to create columns was different -- since there are 16 entries in this category, this category would not have columns yet under VaultWiki 3. However, if you had a category in VaultWiki 3 that had at least 28 entries (instead of VW4's 13), you would have witnessed the same behavior. VaultWiki 4 lowered the threshold for columns in order to reduce the amount of scrolling needed in small categories.

Yes, I see your point. But does this also calculate Letters, as these are also have visual positions in the columns which affect arrangement?

This does not include letters in the calculation. I have changed this to an improvement request.

Letters will be part of the calculation in 4.1.x. The margins and sizes of the letters might be different from the category contents, but there should be some visual improvement. Theoretically it should work, but if there are still problems in extreme cases, like when there is 1 letter in the first column, 12 in the second column, and 2 in the third column, then please open a new bug report at that time.