Try getting the trackpad cable replaced. The part is relatively cheap and easy to replace.
That cable is very common to go bad on any MacBook Pro model in 2015 due to the design where the cable can easily get damaged by debris due to the placement of it being on top of the battery and right under the removable bottom cover.
The trackpad cable has an I2C data line which has the data signal from the keyboard going to the trackpad first which goes through that cable, then back to the main board.
When that line is cut both the trackpad and keyboard (sometimes it's either or both) will not work.
And yes those errors are most likely related to trackpad cable too. Don't take it to apple yet until you've tried replacing the trackpad cable.