You need to use the presets that VSL provides for each library that are located in your VSL Custom Data folder. So for instance, with the Appassionata extended library, for AS violins, you would use this preset:
VSL Custom Data/Expression maps/VSL_Str._Expressionmaps_v/Strings VI-Presets VST-Expression/Appassionata Strings/AS I+II - extended/AS_Violins_L2+II.fxp.
I have not had problems with Legato using these presets and the Doricolib file I posted.
For pizz. and nat. you may need to add some nat. techniques in judicious places. This is because exclusion rules don’t yet work in Dorico. Also, if you are using VE Pro, there was a bug that articulations on the first note of flow did not get recognized all the time. I think this has been fixed, but since I have worked around this bug, I am not certain this is the case.