Wife changed valuation after Form E accepted

My wife and I have a conditional order and are at the point of trying to negotiate division of assets. We both filled in form E documents some months ago and eventually reached agreement.

However in the settlement proposal her solicitor sent me, one asset valuation was significantly less (about £30k). This is a company we own together. She had presented one valuation on the Form E which was uncontroversial and I agreed to ages ago, when I questioned this discrepancy I was told she'd been advised a different valuation method was more appropriate. I've never been given any prior information to this point until an email from the accountant dated last week supporting this.
I consider this quite dodgy, especially that it was slipped into the proposal without being noted. Form E includes a statement of truth, surely while things can be updated based on new information, this must be done transparently?

I totally disagree with the change but wonder how to respond. Her solicitor should have taken values from our agreed Form E, but it would presumably be bad to suggest they have acted improperly - making accusations at a solicitor seems pretty dangerous ground!