I’ve made use of Gerrit’s hard work and added a dice roller tool to the Google Sheet version of the character keeper / reference sheet.

It’s not the most intuitive feature ever, but it does work and doesn’t require a script or any special permissions. Just follow the instructions on the Setup tab to generate a bunch of random numbers. You’ll be able to roll dice by selecting the character and stat to roll with (so the modifier will be included) and then clicking one of the checkboxes on the left edge of the Characters sheet.