FODT Validation

Re: Recent mention of ODF Validator

Is there a validator for FODT files?  Can the ODF Validator be upgraded to
include the flat format?

Failing custom built fodt:
https://drive.google.com/open?id=1BPAJqGTFmeNLb80PRKcfcGt_4Qwy136p

Similar template file that loads. fodt:
https://drive.google.com/open?id=18T9nEKt8bjckin0d7iYRuI4FEDhSFOVI

And an example file with actual text in it: (This file includes copyrighted
material released under a Creative commons license. this snippet doesn't
include the license.)
https://drive.google.com/open?id=1LZvBC_xWUQ_neBhwXgh4FbIvxsAqs6ae

There is only 1 change to a scaling factor on 1 font setting difference
between them.  This specific style is the default style, but I can't figure
out what fails.

I'm building Custom stylesheets into .fodt files.

I have what appears to my human inspection to be valid file that fails to
load with no useful error. I know Its related to I'm scaling fonts, and
this sheet scales (superscripts and has a width scaling) even the default
font. But as far as I can tell this is all valid, yet LO fails to load.