Importing information with Relationship fields - data not populating

Hi, I'm having a problem with exporting/importing information from one app to another in a different workspace. I can't simply clone it as I have 14 apps to combine into 1. The app is called Coaching Log.

The fields include Student name, date, activity, Teacher, and so on. Student and Teacher are relationship fields to other apps. (Students and Workforce)

When I do the export, the Teacher name exports fine (with a lot of information such as address which I don't need). 
I need to manually enter the Student name as it only exists as a field/relationship in the new app.

When I import, the Student name does not populate despite being mapped. I tried turning off duplicates and it populated the wrong app (Students) instead with a whole lot of empty records, only the name. The Teacher name didn't import at all.

Is there a way to get multiple records to import which have the same Student and/or Teacher name? I need to combine all 14 apps this week, and I'd rather not have to import 1, manually edit 40 records, then go on to the next and so on.

Even if I can only export and import from 1 at a time, not having to edit all the records afterwards would save me hours. Ideally I would be able to export multiple apps and combine them, then do one big import, but obviously this can't happen if every record has no student name when it imports.

I've attached screenshots showing the spreadsheet I'm using, the attempt to use the Student name (showing that it will populate the wrong table if I continue), the field mapping showing the Teacher name and no Student name option, and the import with no names filled in. In that last screenshot, there are some student names from where I've imported and edited before - as you can see the Teacher name did not import there either.

Please help! There must be some way round this other than manually editing every single record to add Student and Teacher names as I have over 500 rows to do in total.