Generally speaking, when the recommended release seems out-of-date, its a safe bet to use the latest patch in the same branch.
For example, EXOS 15.6.3.1-patch1-5 is "recommended" for several products in the matrix. However, EXOS 15.6.3.1-patch1-9 is available - that would be the best choice.
To take it another step, depending on release dates, EXOS 15.6.4.2 might be a better choice. It looks like that was released in December, and based on that, it should include all fixes that were in 15.6.3.1-patch1-9. You'd want to refer to the release notes to confirm this though.
Hope this helps!