[Baertram]

Please ask the author in the addon's comments.
https://www.esoui.com/downloads/info....html#comments

Afai can see the PriceTable.lua file will be downloaded via the client.exe file and it automatically detects which server you are playing on. So this can only be answered by the dev of the client.exe file then.
Or maybe it contains both data, EU and NA.

For ingame the addon detects which server you play on via function

function TamrielTradeCentre:GetCurrentServerRegion()
	local serverRegion = nil
	local lastPlatform = GetCVar("LastPlatform")
	local lastRealm = GetCVar("LastRealm")
	if (lastPlatform == "Live") then
		serverRegion = "NA"
	elseif (lastPlatform == "Live-EU") then
		serverRegion = "EU"
	elseif (lastRealm:find("^NA") ~= nil) then
		serverRegion = "NA"
	elseif (lastRealm:find("^EU") ~= nil) then
		serverRegion = "EU"
	end

	return serverRegion
end

Perhaps the detection functions are not working properly, ask the author why he isn't simply using "GetWorldName()" ingame to detect the server.
It returns "NA Megaserver" or "EU Megaserver" and he could simply strip the " Megaserver" instead of checking for CVAR values of the last chosen realm and platform etc.
Maybe LastPlatform is not returning live-EU anymore and only returns live,a nd thus the addon thinks you are on the NA server.

But perhaps he got reasons for this code to be used instead of GetWorldName()