The collected editions you mention fall under urtext provisions of copyright law in the EU, which means they are optionally protected for a maximum term of 30 years from publication in member states which address such editions in their laws. As far as I know, only three EU countries address editions of this nature, all of which have shorter terms: Germany (25 years), Italy (20 years), and UK (25 years on "typographical layouts"). While the general consensus in Canada is that editions of this nature fail to meet the "threshold of originality" to qualify as an "adaptation", there have not been any court cases which directly address the issue of whether they meet the threshold or not. Also, the poorly-written attempt in Canada's law to enact a "rule of the shorter term" for works of non-NAFTA origin (which has held to apply only to works with more than one contributor) would actually apply to such editions as there is always more than one contributor involved. (the original composer plus any editors). The "threshold of originality" situation in the USA is similar, but a problem arises with such editions that were published with a compliant notice before 1989 and/or registered and renewed with the copyright office. Registration in particular is held to be pima facie evidence of the validity of a copyright claim, which means the burden of proof falls upon the plaintiff to demonstrate to court that the edition fails to meet the threshold of originality as described in the USSC decision Feist vs. Rural. Fortunately, a fair number of such editions failed to meet the notice and renewal requirements. Even better, because they are public domain in their country of origin, they are not eligible for "restoration" under the provisions of GATT/TRIPS.
As I recall, both the Machaut and Praetorius collected editions were issued in the 1920s and 1930s and fall in the last category mentioned - free in the USA, the EU and Canada. Another real pitfall with respect to the USA status of very old works like these is the whole question of when "first publication" took place. With Praetorius, it's not a problem as most of his considerable output was actually published in his lifetime. Machaut's work is different. If, for example, a Machaut work you wished to arrange was first published in 1933 with a valid notice and duly renewed 28 years later (and there were a few European publishers who were incredibly good at making sure this was done), that work would still be under copyrght in the USA until 2029 - despite the composer being dead hundreds of years. (Ouch!)