The only thing that really matters for any eBay shipment is the last estimated date for delivery as stated on the listing page and any communication the buyer may receive. What happens or what doesn't happen between the time that the buyer pays and that date is pretty much immaterial. The value of tracking has been oversold to buyers, in my opinion. It gives the illusion of control over the shipment, and when the buyer realizes that they don't have control, they may freak out, as your buyer seems to be.
I realize there's probably not a delicate or tactful way to put all that to the buyer. Let them know (they may not) that eBay International Shipping is a new thing for eBay Canada and there may still be some bugs in the system. Remind them that there was a delivery date range in the listing and eBay can't do anything for them until after the last date. The shipment is eBay's responsibility now, not yours, and if you find out anything more about the package's progress, you'll let them know.
You could try using your tracking number on the Parcelsapp site to see if it's going to link to the tracking information for the next leg of the shipment. Look for information on the side of the screen that gives carrier information.
Keep us posted, and good luck!
EDITED TO ADD: To actually answer your question, if the Canadian eIS hub works in a similar manner to the US one, there's no way to contact it directly. You may want to try contacting customer service through online chat or the social media links on the desktop version of the site at the bottom of most eBay pages, but they may not be able to tell you much more than what you already know. What's the address of the hub, anyway?
