Music Chef puts out some useful videos for Dorico and Cubase. This one is well worth watching if you struggle to debug Expression Maps in Dorico.
Music Chef - Debugging Dorico Expression Maps
Most of what he covers I already knew, and I have been using the tooltips from the Key Editor’s Playback Techniques lane for this purpose for a long time. But he gave me a more systematic and complete understanding of the various entries in in the tooltip, especially clarifying the Internal Technique entry.
I had previously thought it only reflected any hard-coded left-panel score techniques like Staccato, Staccatissimo, Staccato Tenuto, and Tenuto. He clarifies that it is any playback overrides from Playback Options (note length or dynamics) or from Expression Map entries. To me this expanded my understanding, and I appreciate it.
Anyway, hopefully posting this helps somebody.