It seems that you are not picking the right Roboto Font in Justinmind based on how certain characters are rendered (see attached document).
How can I select the 'official' Roboto from Google?
I imported my Sketch file and all the text is messed up. This seems to be because your do not support key Google fonts including Roboto. I cannot remove Roboto from my PC, it's used pretty much everywhere. What is the fix? Here's hoping this is one as otherwise I'll have to find a different tool.