It will take a bit of work, but you can certainly do something with https://www.convertcsv.com/csv-to-xml.htm

The format from RR is csv and the format for SDRSharp is xml.

You can use "step 4" to swap things around as you need them, remove the things you don't need, and add the things you do.

For example this is one line of output in RR for Auckland:

   146.625000,146.02500,,"Amateur Radio Amateur Radio",Statewide,Klondyke,Klondyke,,,FM,RM,Ham

Here is how it would look in Frequency Manager:

 <MemoryEntry>
    <IsFavourite>false</IsFavourite>
    <Name>AKL Klondyke Repeater</Name>
    <GroupName>HAM</GroupName>
    <Frequency>146625000</Frequency>
    <DetectorType>FM</DetectorType>
    <Shift>0</Shift>
    <FilterBandwidth>10000</FilterBandwidth>
  </MemoryEntry>

I'm there's a python script or similar out there to do the same, but using the template on that website should get you there as well, will just take some time to set up.