Can I read an xml containing horizontal geometry for an alignment chain (in N,E) and have it write out a list of points along the alignment(s) (in lat,long)?

Yes. Use Reprojector, PROJReprojector, CSMAPReprojector, or any other reprojector you need to get your data to Lat/Long, then use the DistanceMarker transformer from the FME Hub.

Then just create the attributes you need (with @XValue, @YValue).

Thanks a lot caracadrian! I'm brand new to FME, so not sure how to do any of this year, but I'll will give it a try. Any suggestions on how to learn how to build this workflow?

Short answer is https://www.safe.com/training/recorded/

Long answer: figure out what kind of xml you have, use the apropiate reader, get the geometry (GeometryReplacer maybe), create the points along your line with DistanceMarker, reproject to a lat/long projection, use attribute creator to create Lat and Long attributes from point coordinates. So: XML Reader - > DistanceMarker - > Reprojector - > AttributeCreator - > Writer of your choice

Awesome - thanks for the help!