Since whether we need to be concerned about the EIC is essentially entirely in our hands, we need a set of guidelines for making our judgement calls on it. I would say that we can make this judgement based upon, essentially, two factors:
- Is the EIC impeding the prosperity of the populace?
- Is the EIC destabilizing the political stability of the province?
If the answer to both these questions is "no", then the EIC is completely fine. Remember that our remit as a Grey Magister is to serve the Empire,
not to serve any specific subdivision thereof. This means that as long as the people are prosperous and Stirland retains the ability to react to crisis situations demanding rapid, centralized action for the sake of the common defense, we have no business butting into the situation while wearing our wizard hat.
Point 1 is basically held in check by Wilhelmina's strong ethics and keen understanding of what economic policies will lead to widespread prosperity and what would cause suffering to the common folk. The moment she dies and the EIC gets a less savvy or less ethical administrator, this will crumble; to head off this circumstance it would be prudent to ensure that there is a worthy successor arranged for her. Hopefully she will manage this on her own but if not we can certainly give her a nudge. No further action should need to be taken on this matter, because honestly the Empire has always depended upon the personal ethics of the powerful to keep its populace from suffering.
Point 2 is more interesting. The big concern about stability was that Roswita was reducing the Elector Count's incomes to the point that she might not be able to maintain control of matters long-term, and that would of course cause a weak central authority and degradation of ability to handle catastrophe. However, we don't actually care about the authority of the office of the Elector Count being undermined, as long as the likely result of that erosion is not widespread chaos. Notably, the EIC being owned primarily by the
nobles of Stirland (as it now is, discounting Mathilde's shares) means that we're basically looking at several noble families allying and putting themselves into a position to form an economic and political bloc which will be able to pressure the Elector Count to their advantage, and potentially eventually force a replacement of the current ruling line with a member of their own families. And that... isn't widespread chaos. It's just politics as usual, nobles striving to advance their own position and rank. The Grey College has no grounds upon which to interfere with this matter, as doing so would be blatantly taking sides in a nobles-vs.-Elector political scrum when neither side of the issue is in any way involved with enemies of the Empire or matters over which the Grey College has remit.
To conclude, Mathilde should be keeping an eye on the EIC but I'm pretty sure at this point the most action she should be reasonably taking is to sternly remind everyone to keep the good of the Empire in mind at all times, to make sure that their successors are also going to do the same, and that she's watching in case they forget.