After some further analysis I would like to address a couple of errors in my previous post:
1. The setting "analyse.main.search.coarse.type" is in fact "analyse.main.search.type" (an easy mistake to make) which cannot be modified in any way in the settings of SVP 3 and SVP 4 and the default values are again 4 and 2 respecively. This has a slightly different effect of changing the search type of the finest level of interpolation instead of the coarse levels.
2. I somehow overlooked comparisons of several consecutive frames from the same source material which revealed frames that did not match, due to another script parameter. This was surprising since I managed to select 3 test frames from different source materials which did match, amongst the pool of matching and mismatching frames in each source material.
The parameter in question is "scene.mode" and in fact made another large difference in artifacting on those frames which did not match. The value used (with the profile settings given previously) in SVP 3 is 3 and in SVP 4 is 1. This is very strange since according to the documentation this controls the overall interpolation mode and should be set to 1 to force 1m mode and 3 to force adaptive mode. However one can alternatively keep adaptive mode and change the threshold values for switching from uniform to m1 and m2 in order to force 1m, 2m, 1.5m modes (see documentation on "scene.limits" for info on this.) SVP 3 and SVP 4 already have the threshold values both set to zero which forces 1.5m mode, but it appears that the value of 1 used for "scene.mode" in SVP 4 overrides this to m1 mode (more artifacts).
Therefore for now the value of 3 must also be specified for "scene.mode" in the override.js script to prevent SVP 4 from using 1m mode instead of 1.5m.
This appears to be an error in how SVP 4 generates scripts using 1.5m mode and should be fixed by the developers. It would also be nice if the "search range" had more options which correspond to smaller steppings in the value of "analyse.main.search.coarse.distance", such as a slider like on the main screen. This would allow, without much added confusion, better tuning that can allow us to get the same settings for SVP 3 "medium" and "large".
Home this helps!