About the UE 4.26 update, yesterday DTG Matt said:
"We're on the latest released version of 4.26 as of the current one coming out soon on Steam (and already out on Epic).
4.27 is not out yet.
5.00 is nowhere near out yet.
Historically it is a fools errand to start big development works on a major update to the engine because there will be many other changes and fixes. When we upgraded to 4.16 for Great Western, we ended up having to take a LOT of fixes from the unreleased 4.17 and even a few more fixes from the unannounced 4.18 to make it all work. We don't rush to do engine upgrades, it's far more dangerous than the benefit.
Also bear in mind, an engine upgrade to the game is around 6-8 months of engineering effort (or at least that's what 4.23 to 4.26 has been). It's not trivial in the slightest.
Personally, i'd have rather spent that 6-8 months on new features in the game, but upgrading in this case was essential for various reasons so here we are."