The following program works fine for writeBlue or writeGreen, but fails for writeRed as soon as the tone function is called once. I tried to work around it by using writeRGB but the bug doesn't go away even with using that. The random delay code below just makes it easier to observe, and isn't related to the issue.
pert:
Why do you think it might be "too late to fix"?
Do the people who are responsible the Esplora library code read these forums? Or do I need to consider finding the library code myself and trying to fix it myself? Where would I look for it?
No, they usually don't read the forum. This is mostly a place for the Arduino community to talk and help each other.
It's certainly worth having a look at the library to see what you can do. I've never used an Esplora. I know that using Tone does interfere with PWM on certain pins.
Sketch > Show sketch folder - this will open the Esplora library's EsploraAccelerometer example sketch folder.
Navigate up three folder levels to the Esplora folder. You will find the library source code in the src subfolder. You can open those files with a text editor and edit them as you like.