Thinking of the problem in the core, of column mode select not coping with varying line lengths, this is a possible partial workaround :
Suggest: Add a column-mode paste.
With that, you could use normal copy, which gets all lines of varying lengths, then CMP append to any block.
in the few instances where that is not a solution, you still manually add spaces to the last line, to match the longest line above, then use normal Column Select on that block.
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Thinking of the problem in the core, of column mode select not coping with varying line lengths, this is a possible partial workaround :
Suggest: Add a column-mode paste.
With that, you could use normal copy, which gets all lines of varying lengths, then CMP append to any block.
in the few instances where that is not a solution, you still manually add spaces to the last line, to match the longest line above, then use normal Column Select on that block.