Most employers will not look too hard for the supporting requirements for an endorsement, ie they will probably look for the endorsement, but not the ground and flight that goes into it. However, if they have reason to be suspicious about something, they will pull out all the stops.

The FAA, on the other hand, will crucify you if they ever have a reason to dig into your logbook. The record of ground training does not have to be in your logbook...if you can get hold of the guy, ask him to write it on a piece of paper and mail it to you. That way you'll have it if you ever need it.

I suppose the training that needs to be logged does not necessarily have to be on the ground...but you need a written record that all of the required knowledge items were discussed. I just copy the items verbatim out of the regs.

Also regional will not care about the high-alt endorsement...that is required for PIC's, not FO's and it is covered in your training anyway, at least for their legality purposes.