Web Speech API wrong time recognition

want implement a web application that recognize the text in italian. I’m try to use this library:

Web Api Recognition

There is a problem try to use this library. If I try to speach “tre meno un quarto” the library sometimes recognize this time “2:45” (that it is correct), sometimets recognize “3:45” that it is not correct.

This problem is it also happens with other times. There is a mode to fix this problem ?