Dear Dimitri,
You can easily import metadata from any xmp files to jpeg and TIFF images. I am not familiar with the XMP editors, but there are ways that you can edit the metadata in the software. To transfer the data from an xls, xml or csv file, you can use clipboard softwares. With clipboard softwares, you can simultaneously copy several keyword sets, files, and even images in clipboard and paste them whenever you need them.
Through some search, I found
Kalimages XMP Editor. But I frequently use the free M8 clipboard software from
M8 Softwares. However, I guess that there would even better options in XMP Editors.