>By definition, every company that exists has a "biggest" problem internally.
This is absolutely false. Problems are not all measured along the same axis so that two problems can be directly compared to each other. If I have one problem related to customer acquisition, and another problem related to legal/regulatory issues, they are both problems but neither of them has to be bigger than the other.
Furthermore saying I don't have a singular biggest problem that keeps me up at night isn't the same thing as saying I have no problems whatsoever.
Every business has many problems they are working on along many dimensions: legal, sales, development, hiring, accounting, you name it... they are all important and separate problems. Usually if one area of the company has such a big problem compared to the others that it can be considered the "biggest" problem then it's a sign of a poorly managed company. Most decently sized and well managed companies do not face such single-dimensional or dramatic issues. Problems manifest themselves locally and are dealt with locally in a fairly boring/undramatic manner.
>Things are generally pretty good but moving to Salesforce has caused some frustrations that we're working through
Exactly, it's an answer that satisfies the question and says absolutely nothing to the candidate. I could give you some other menial answer "Yeah things are good but the biggest problem right now is integrating our build system with a new platform we're targetting..."
Satisfies the question and really tells you nothing of value. Instead I'd suggest asking questions that can't be satisfied superficially and that actually reveal valuable information.
Spend your time on tangible questions that can be used to make a concrete decision about whether you want to work there... clarify details about work conditions, work hours, compensation, career progression, management structure, meetings, those things matter and are reveal facets of a company's culture.
Knowing a company is moving to Salesforce or some other BS a company says about itself is not going to tell you anything worth knowing, it just wastes time for the both of us.