if the iNat staff don’t have a backup readily available that contains the data and aren’t willing to restore a backup (which i understand, since it would be a big task), then it still may be possible to get the information from another source.
specifically, if your friend’s photos were licensed (as opposed to all rights reserved), then it’s very likely that the basic parts of the observations (date, taxon, location) were saved in the AWS Open Dataset metadata, and it’s possible that because photos files currently aren’t being deleted properly, you might be able to recover the image files.
the biggest issue is that if the observations had some sort of geoprivacy applied, the AWS Data Set metadata would reflect the obscured coordinates rather than the true coordinates of the observation. also, this set of data wouldn’t include any observations that didn’t have photos.
it’s also possible the data might exist over at GBIF (if it hasn’t been deleted already) or in an old copy of the DWCA export to GBIF. the requirements for an observation to be exported to GBIF (research grade + a permissive license) are a little more strict than the requirements for the AWS Open Dataset, but if some of the observations made it to GBIF, then GBIF will have more detailed information from the observation than just the basics covered by the AWS Open Dataset. (it’s possible that iNat staff may be able to provide you an old copy of the DWCA Export file, even if they can’t realistically restore an old copy of the iNat database.)
in the future, if you want to keep a better record of the observation data (without images) just as a backup, the most basic way to do this is to periodically run the iNat CSV Export for your own observations. there are other ways to get more information, but as i noted before, it’s not necessarily easy. so if you want to do something more complicated, it’s worth knowing what you would intend to do with the downloaded data. (in the case of the lost data, would you try to reload the data? or would just refer to the backup and not try to reload the data into iNat?)