on thin ice vs unconfirmed

on thin ice

adv
  • dangerously, hazardously, delicately 

prep
  • In a dangerous, hazardous, or delicate situation; at risk. 

unconfirmed

adj
  • Not having undergone the ritual of confirmation. 

  • Not finally established, settled or confirmed. 

How often have the words on thin ice and unconfirmed occurred in a corpus of books? (source: Google Ngram Viewer )