1. "Tier" is not informative at all - you have to read all headings at Crafting to understand it's name.
Category:Science I craftables and so on - any comments about this?
2. "Objects" was used only to distingush it from other categorization, which is orthogonal to it:
3. Category:Craftable Objects by Crafting Stations is a container category; a category consisting of other categories, a category that shouldn't contain any single page.
I don't know if "Category:Craftables by Stations" would make less or more sense for readers.
Category:Crafting Stations was named as it's named. I simply used it's name. Please start a separate discussion if you want to discuss it in detail.