I have attached 3 modified versions of your files. I used ExifTool to remove the original subject and keyword metadata. I then re-wrote the subject/keywords to the "clean" files using ExifTool. This is purely as a test to see if your client has any different results with metadata generated in other software:
exiftool-subject.jpg = only subject metadata, no iptc keywords
exiftool-keywords.jpg = only legacy iptc keywords, no subject metadata
exiftool-both-subject-keywords.jpg = both forms of metadata
Don't open/resave these in Photoshop or other Adobe software (otherwise the metadata would be invalid for this test), just see how they are handled as is.
It will be interesting to see if your client has issues with these files.
Please do come back with the findings!
Hey Stephen,
sorry for the late answer, the mills grind slowly here. The client said they'll tag metadata themselves after data delivery from my side without further notice of reasoning, which is cool because I don't have to deal with tagging anymore 🙂 and I don't feel inclined to dig deeper unless they want me to. I believe they found out the obvious – their proprietary approach doesn't work with the XMP Standard, therefore it's best to tag within their system than not being able to correctly capture externally tagged files.
Thank you and best regards
Andre