Improving bulk-process catalogue items

[zzszarka]

Is your feature request related to a problem? Please describe.
In bulk-process catalogue items, I find it difficult to verify how many of the pasted items have been matched (will be affected), when I paste many items into the left side.
It is also difficult to confirm which pasted items have been matched to what catalogue item.

Describe the solution you'd like
In order of priority:

1. A count of items on each side
2. Highlight unmatched items on the left in red
3. In-line layout: items on the same rows across both sides, allowing for multiple matches

Describe alternatives you've considered
A clear and concise description of any alternative solutions or features you've considered.

Additional context
Add any other context or screenshots about the feature request here.