I don't think that would do it either; I think that would give the EIC a bunch of money, but not enrich Mathilde specifically. Mathilde has never gotten lump sums from EIC actions, it's only changed how much money she gets from the turn income as dividends from her ownership. And since the ithilmar trade expressly doesn't represent an income stream, but rather a one-time injection of cash, I'm doubtful that the ithilmar action would put money in Mathilde's pockets as opposed to Wilhelmina just investing it in stuff that will generate income streams.
I mean... we didn't buy them with the expectation they would be immediately useful? The point of Barak Varr last turn was to get a targeted purchase on Metallurgy and the other two topics were just gravy. Metallurgy was immediately useful, but we didn't have ideas for two other immediately-useful topics, so we grabbed Bretonnia and Athel Loren because Barak Varr gives you three. The whole point was to have background info for stuff that would probably come up eventually, so criticizing that purchase for not accomplishing someone nobody said it would accomplish feels odd to me.
From the way people were talking that eventually was supposed to be in one turn, but then we figured out that we do not need the Bretonians