The window opens with all professions except Leatherworking in the Spanish version.
As you can see here, it opens Cooking without problems.

But here, you can see that it does not open the interface with Leatherworking.

Any ideas? Maybe it's because of the double translation that the game uses for the Leatherworking profession, and that's why it's not finding the profession.

In SkilletData.lua lines 68-83 the following table exists:

--
--  a table of locale specific translations by id
-- needed to fix Blizzard inconsistent translations
--
-- [tradeID] = {locale, old, new}
--   locale is what GetLocale() returns
--   old is the return from GetSpellInfo(tradeID)
--   new is the return from GetTradeSkillLine() when the tradeskill / craft is opened
--
local TranslateList = {
	[4036] = {"frFR", "Ingénieur", "Ingénierie"},			-- engineering
	[3273] = {"frFR", "Premiers soins", "Secourisme"},		-- first aid
	[2108] = {"esES", "Peletería", "Marroquinería"},		-- leatherworking
	[3908] = {"esES", "Sastrería", "Costura"},				-- tailoring
	[2108] = {"koKR", "가죽세공", "가죽 세공"},					-- leatherworking
}

As you can see, there is already an entry for leatherworking in the enES locale. Since it isn't working for you, Blizzard may have messed with their translations. I need from you the exact output of /dump GetLocale(), /dump GetSpellInfo(2108), and /dump GetTradeSkillLine() when Blizzard's leatherworking UI is visible.

Feel free to edit the table yourself to verify that it works. Unfortunately, I can't test it myself so I will need your help.

If the line numbers are slightly different it is because the current released version for Classic Era is 1.74 (or 1.75-alpha4 which will work on both 1.14.3 and 1.14.4) and you are using 1.70. The table in question hasn't changed since 1.70.

I can't fix this for everyone without input from you. Please reopen this issue if you are willing to provide the necessary information.

I'm not the post owner, but here is my game output:

Maybe this can help:

@camador, Thank you for your help!

The output you provided appears to be identical to the existing entry in the table. I have attached a modified Skillet.lua to add some additional debug statements. Please install that file (while WoW is closed), type "/skillet tabledump on", "/skillet debuglevel 2", open Leatherworking, and give me the debug output again. Please also attach your character specific saved variables file Skillet-Classic.lua which will contain the debug output with the special characters in the names.

Skillet.zip

You can type "/skillet debugoff" and "/skillet cleardebuglog" when you are done so the debug output doesn't spam your chat.

Sure, here they are:

Skillet-Classic.zip

This is fixed in Skillet-Classic-1.77.

Please change line 82 in SkilletData.lua from:
[2108] = {"koKR", "가죽세공", "가죽 세공"}, -- leatherworking
to:
-- [2108] = {"koKR", "가죽세공", "가죽 세공"}, -- leatherworking

I need to use a different table layout which I'll work on and release a new build.

Yes, that did the trick.

New version is working as well.

Thank you!