I’ve gathered together a couple Perl scripts from Graham for creating and manipulating Blorb files, improved them, and put them on Github. For scanblorb.pl, I gave it all the functionality of rezrov.c (dump Blorb contents) and added the ability to analyze Blorbs made for ADRIFT games. Perlblorb.pl (now pblorb.pl) has some improvements on MOD and OGGV handling. More tools will be added soonish. You can get all this at gitlab.com/DavidGriffith/blorbtools.
It would be interesting to know the compatibility of the different interpreters with the Blorb format. The resizing of an image, for example, is not done with SDL Frotz whereas it is with Windows Frotz which does it by applying a filter (I don’t know if the Blorb format specifies the use of a filter or not for resizing).