Sent a PM to you
I'll prefer to answer here if you don't mind because the discussion might be interesting to others as well.
Where do I check compatibility? Can I correct nodes not functioning within max from SD5? Can I do it simply?
There is a "Projects" tab in the "Preferences..." panel in the "Tools" menu, with an option named "Compatibility Mode" which is set by default to "Substance Engine v5". If you set it to "Substance Engine v4", the graph view and the menus will highlight (in yellow) all nodes that are not compatible with the engine of Substance 4 (and therefore with the current integration in 3DSMax). It might then be possible to replace the nodes which are not compatible with some that are, but there is no automatic way to do so, nor any guarantee that it is possible to find a perfect replacement. In any case, it will probably not be simple.
Is there an ETA on when this long-standing issue will finally be resolved?
Unfortunately no, we don't have an ETA.