Thanks for following up - I've got nice figures now, after correcting on space and playing a bit more with chauffeur.
Tedana does a lot of processing with python. I am not sure that carrying over AFNI header information is a priority :( Fortunately, it is effectively a last step for me, and I keep the volreg output around for further QC. I do believe it has been noticed by them however, so there is a hope. And yes, it doesn't move the data around at all. Rick's fix should resolve the problem nicely, as correcting the space has definitely got things working for me.
Thanks, and keep up all the awesome!