Not enough contrast in Check Spelling dialogue box
InDesign CC 2017's Check Spelling results interface is fairly unreadable. In the "Not in Dictionary" and "Uncapitalized Sentence" box, more contrast is needed between the text and background shading. This is true in all appearance settings (dark, medium, light).
Please update InDesign to the latest version, InDesign CC 2018 (13.0) for the fix of the issue.
Susan Shultz commented
An update is not an option when using an additional plugin such as XMPie. My department cannot update the Adobe InDesign document unless/until additional software providers can catch up. I would think that InDesign 2017 would be a recent enough version that you would still be supporting it.