While the mod works in genral and all the features are available as described, it’s just oooold.
You see that it was started 10 years ago. The look and feel is just clumsy. The default inventory was improved a lot since then and has a robust search and an own crafting guide. Also, the (now) common sfinv makes a lot of Uinified Inventory’s features redundant because mods added tabs to the default inventory for their functionality.
If you want to use a modern replacement for Unified Inventory maybe check out i3. Or simply stick with the default inventory that got improved since Unified Inventory was created.