In tools>customize>keyboard there's no option to paste unformatted text like with writer. You need to use ctrl+shift+v
I can confirm with LO 4.4.2,
In Writer we have Ctrl+Alt+Shft+V (Not Ctrl+Shft+V as the table with shortcuts in the Help mentions - that has been changed half a decade ago to start Paste Special) Suggest to use Ctrl+Alt+Shft+V in Calc too
Migrating Whiteboard tags to Keywords: (needsDevEval) [NinjaEdit]
Works for me with LO 6.1.0.2 and Win 10 also in calc.