As someone who has multiple retainers in the major cities, I have to do a bit of digging to find out which retainer sold an item if they are in the same marketplace (like Gridania).

I'd like to suggest that this message include the name of the retainer who sold the item, so for example, it would say:

The (item name) that you put up in the (city name) markets was sold for (price) by (retainer name). So it would look like:

The orchestrion that you put up in the Gridania markets was sold for $100,000 by RetainerOne.

This way I can go directly to RetainerOne and withdraw the funds.