We are a small three-person team dealing with data analysis working in a software company. Until a few months ago, it was just me and another colleague, both of which have a technical background (engineering/data science).
A few months ago, we were assigned a product owner that joined the company: their qualifications included a Ph.D. in a natural science (not CS) and various data analysis tasks in R, so it seemed to be a good fit since we needed someone on board who was familiar the content matter to some degree to take on some of secondary aspects and communication matters (aside from the usual product owner aspects). Their experiences prior to joining were (as far I know) mostly in Academia as well as data analysis at another company.
We only met the person once prior to them starting, and it wasn't for a technical interview - they were OK'd by another team prior to us starting at the company.
On a personal level, we get along with the person great. Unfortunately, as we dealt with the person more and more, we ascertained that they are lacking in some - in our view, rather basic qualifications. For example:
They are expected to analyze and come up with a product vision and ideas, but many meetings on the topic had to be steered almost entirely by me and my teammate for it to be fruitful at all (little to no methodological know-how).
They are often not very well prepared for said meetings (and others).
To complicate matters: the person is not a native speaker and often makes grammatical errors in writing and speech. While we don't have any issues with this internally (it's entirely possible to hold a normal conversation), the person is also responsible for external communication with potential clients which, to be honest, does not seem very professional. We gladly point out or offer to help out with this, but our responsibility to the team should lie within what to communicate, not proofreading for spelling mistakes.
Lastly, and the impetus behind this question: we have had several meetings where we asked for some input to determine some values that we use for various features. We have provided tools, infrastructure and information on how they might be able to determine these values. We've had to explain these things numerous times and it seemed that the person was unfamiliar with some basic statistical/numerical analysis methods (or at the very least, unable to effectively apply it).
The person hasn't been on board long and they needed time to understand our domain, which is completely understandable. However, their qualifications just don't seem to translate to hard skills which help us very much.
I'm worried that if we allow the above situation to fester, it's not only going to hurt our team standing in the company (since communication is mainly their role) but make our resulting work suffer as well since it does eat away quite a bit more of our time than expected and, frankly speaking, is very demotivating.
We haven't actually spoken to the person about this since we're not sure how we could possibly provide this kind of feedback ("How did you reach your level of qualification without knowing XYZ?" - not verbatim, obviously) tactfully.
How can we resolve this situation?