If you already have the keyboard track in reaper and you just need to line it up with the BIAB tracks you could do the following:

1) Explode the view in reaper (click on '+', bottom right)
2) Place the cursor to where the keyboard track needs to start.
3) Select the keyboard part by clicking on it
4) Right click and choose 'Nudge/set items'. You can shift right or left as needed. Just shift until it lines up properly.