We banged our heads on the walls trying to find where this issue was..
Basically our company computers are set to German language. The from and to Timestamps and the confidence value were really weird until we realized this afternoon that we should change the culture of the computer to United State to get the correct values.
I tried to parse the double values from SpeechToText.cs with culture info but it gave me some parsing exception and was not working at all.
On my computer (set to United State) I get values like this for confidence :
On my colleague's computer (set to Germany) we get values like this :