Currently, Eden Editor does not show the live results of using attachTo.
This is normal expected behavior, because the init field starts after the mission starts.
But it would be nice if you'd be so kind to add a feature for live attachTo rendering and remember the offset coordinates so that it can be exported as script.
Or better yet, allow an object to be attached directly from the Eden Editor, while remembering the offset, so that it can simply be exported.
There are workarounds however.
That is to make the composition of attached objects, then find their relative offset from the main object and copy them over.
This is rather complicated though.
Another option would be to add an attachTo tool within 3DEN, which would allow you to place two objects down and click attach. Say:
1 - Place two objects.
2 - Right click the object you are attaching.
3 - Select "Attach To".
4 - Draw line to/ select object you are attaching to.
5 - Script works out relative pos with worldToModel and get/setVectorDirAndUp..
6 - WIN
I want to look into doing this but could be something devs are planning on.