Thank you for the investigation. I can imagine what can produce such effect during conversion. CWP has a list of used audio files (names). And the name of audio folder (normally .\Audio). These files are references by index, so 0 - first ,1 - second, 2- third, etc. During all my tests, I had per-project ./Audio and files in it. Also files in CWP was always indexed from 0.
It will not wonder me in case Sonar not really use that "Audio folder" or start indexing from not zero under some conditions. I am away from home this week, so I have hard time to test such thing. Since you have found working procedure, we can just ignore it (may be with warning in the documentation). But we can also find the reason and fix it in a week. I let you to decide.
About vst3. I have uploaded b15. It loads presets correctly for every VST3 I have. I have also downloaded iZotope Vynil in addition. And it restore preset as well. So, I run out of cases I can reproduce myself.
Please do the following:
* create a project in Sonar, with just one audio track. Into FX bin, load VST3 plug-ins which refuse to load preset after conversion. You can put many of them. Do not change anything in inserted VST3, so leave them with default settings.
* create a project in Reaper (DO NOT convert from CWP!). With one audio track. And insert the same VST3s. Also do not change settings.
Upload resulting CWP and RPP somewhere, and let me know the link.
(that way I can check that converter produce from CWP exactly the same settings as Reaper produce itself).
Thank you for testing! I do not really know CWP format. The success and stability of conversion solely depends from the brightness of tests.