No, its a different command.
`SIAddPointOnCurve
adds points as a result of execution, while result of execution of AddPointOnCurveTool() should be an activated 'Add-Point' tool in viewport.
Anyway, I used content search inside dll files inside softimage folders looking for "AddPoint", "PointOnCurve" etc strings and found the correct name for the command. So there are three commands instead:
AddPointOnCurveToolByCVs,
AddPointOnCurveToolByKnotPoints,
AddPointOnCurveToolByBezierKnotPoints
which is kinda logical, since in UI also three commands available. And I tried some name combos before but turned out I was adding 'ByCVs' in wrong place (
AddPointOnCurveByKnotsTool
) heh.
From now on searching inside dlls would be my last resort trick :)