A cavity wall depends on a linkage between the two leaves for stability - hence the tie. Some wall ties (the wire butterfly type and, maybe, some galvanised types) will corrode over time. If this happens you have a problem.
Some wall ties will corrode when they are in contact with some foams - this is not much talked about in this country (but anybody considering buying a house or a flat made of timber frame in which metal fixings come in to contact with foamed insulants would be best advised to have a word with me first).
If the wall tie gives way that's a big problem. If foamed insulant is blown in to the cavity and expands, and pushes the two leaves of the wall away from each other then that is another problem - a bigger problem.
What happens in this country is that technologies get imported from the States, where building warranties and designers liability is far more limited than it is here. The problem with buildings is that when they go wrong they take a while to go wrong. And when they go wrong the owners sell them...which is another story.
I'm not giving anybody specific advice about a specific problem, but I do suggest that all insulants applied to walls require a bit of thought
One thing is important. The guarantee is completely worthless unless it is backed by something big like an insurance company. And the guarantee should cover consequential loss - I hate to admit this, but a solicitor is your best guide to this. Remember that Joe Blow Insulation may not be around next year.....
