Epic had an OK summary of the role.
Ultimately, you can think of it as the oil between the art and programming gears, someone who understands having good art quality but also balancing optimization and performance.
Read through posts in this sub. It's a very common question, and you'll find the answer many times.
The other thing to do is to read job descriptions for technical artists on LinkedIn. They literally list all the skills you need, so all you have to do is sign up to lynda.com or udemy.com and put in the work.
That sounds troubling! You need to talk about expectations with the team. First, get the supervisors to specify everything they expect to produce. Ask the artists what they can do and how they expect to contribute. Establish the gaps between team ability and team expectations. Understand time scales, budget, existing tools. Then work out what you need to do to bridge any gaps in the production pipeline. It might be tools. It might be training. It might be engine work or fx. Whatever it is, you need to gather the information before you can create a plan.
And read this book as fast as you can: Production Pipeline Fundamentals for Film and Games https://www.amazon.com/dp/0415812291