赤心 せきしん can mean something along the lines of "your true heart", but it's not something you commonly use. It's also a name.
If someone would be asking Siri why she is being so honest, they'd most likely use another word.
The sentence どうして「赤幸」に「赤心」と言いますか?would mean: "Why do you say 'Sekishin' to Akakou?"
For it to be "call", you need these particles:
"Siriさんは、どうして「赤幸」のことを「赤心」と言いますか?"
February 7, 2016 at 9:48am