Seedling, the more specific search will not bring up Tanning because Tanning Training is not a Leatherworking specific training. I don't think the training itself is marked as such.
Last time I checked, omniscience was not a requirement for using a wiki. In fact, it would make the wiki useless...
That Tanning Training is not listed as a leatherworker skill in your database is irrelevant. It shows up only with leathercrafting recipes, it can be bought only from the leatherworking guild npc, and I didn't search for exclusivity but include. (Not that it matters, none of the options will yield the expected information.)
I should not require a flux capacitor to manage a simple search like 'Give me all leatherworker training'.
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