Dear Alex,
Thanks for contributing to our forum. Our system does not currently support the use of the Custom Label feature so, when you post multi variation listings through Auctiva, I do not expect anything to appear in the Custom Label within your eBay account from the sales you make for those listings - unless that is something eBay does automatically.
I am actually not quite sure how eBay displays the variation details of items that have sold on the My eBay page, but I suspect they most likely have something in place to let sellers know which variations were purchased for items that use variations.
If you find that this information is not showing up within your eBay account for the items that you have listed through Auctiva, please file a support case to let us know and we look into the possibility of updating our site to accomplish what you have described.
You can reach our customer support team directly by mousing over the “Help” tab within your Auctiva account and selecting the “File Support Case” option.
-Mike