In this recent blog post I said that usually in contracts the verb guarantee is followed by a noun rather than a that-clause. But I’m not sure I can explain the aversion to guarantees plus that-clause.
I think it’s safe to say that “Acme guarantees that Widgetco will comply with its obligations under this agreement” conveys the same meaning as “Acme guarantees Widgetco’s compliance with its obligations under this agreement.” In fact, using a that-clause allows you to use a verb rather than an abstract noun, which results in prose that’s clearer and more concise.
Is the issue that guarantees that seems too colloquial?