Does structuring the deal through a numbered company change who's actually liable?

No — a numbered company is simply an ordinary Ontario corporation that was never given a chosen business name, and it's governed by exactly the same corporate law as any other corporation. Buying through "1234567 Ontario Inc." rather than a corporation with a name doesn't change any of the underlying rules about who ends up liable for what.

What actually determines liability is the transaction structure — whether the deal is a share purchase, where the corporation's full history transfers, or an asset purchase, where only expressly assumed liabilities transfer — and how the purchase agreement allocates responsibility through representations, warranties, and indemnities. A numbered company can be the buyer in either structure, and it inherits liability the same way a similarly situated named corporation would in that same structure.

Owners sometimes assume a numbered company offers some extra layer of protection or obscurity, but it doesn't add anything beyond ordinary corporate separateness that any properly maintained corporation already provides. A business lawyer can confirm that your liability exposure is being managed through the deal's actual structure and terms, not through the choice of using a numbered company as the buyer.