Perhaps an audio feedback like 'The list has been reordered' would be suitable? Audio information is a perfectly acceptable form of feedback for visual impaired users and they generally are used to it and value it.

On a separate note, if the users are blind or visually impaired your UI is problematic by the looks of things. I can identify that bin and the arrow buttons as it is but it's still too small and I have normal vision :)

**Added following comments discussion:**

If I knew more I might suggest you highlight the column that provides the order if it was a table, or write 'ordered by size: small to large' as a subheading above the table etc. It's not uncommon to list how a set of data is displayed above the data and that is screen reader friendly.