An RTR P is issued on the basis of foreign CPL and Foreign RT
Both have to be valid and the validity of the RTR P will be the lower of the two ( either CPL or RT )
Since Canadian CPL has only 5 years Indian RTR P will be issued for 5 years
The max validity for foreign RT conversion cases is 20 years . Thats why Australian and New Zealand CPL +RT cases are given RTR P for 20 years
Lifetime validity is only issued for RTR A after passing both part 1 and part 2
The certificate from the airline with 3 months of RT experience should be acceptable
But you will need to make sure both your Canadian CPL and Canadian RT license is valid
You will receive the renewed RTR P for another 5 years