Tough to know the progression of the defect with the data that you have listed. Looking at the dates how often do you take readings? Either way the data says you have a bearing fault showing up. How are the 2 bearings lubricated? Oil or grease?
Now comes the age old question we always get, "how long will it last?" May need some follow up readings to help determine the timing of when that roll may get changed. The other reading you show from 26-May-18 08:58:37 looks like a much more dominant 1x jumped up also. (guessing at that lower peak)
The pattern points to that internal bearing, who know if your internal accelerometer is still attached. (Could explain the no pattern showing) But only seeing the roll come apart and inspecting the bearings will give you the full story.