GMS2 doesn't seem to recognize these files as GMS2 files, and thus will not allow them to be imported. This is really only an issue when trying to import the "o_AfterImage" object.  In addition to that,  looking at the f_CreateAfterImage GML script, it seems this uses the older version of "instance_create" from GM1.4, which is incompatible with GMS2. Considering the methods this script calls its arguments, there doesn't seem to be a smooth way to transition this script to the modern "instant_create_layer" and "instant_create_depth" functions. Because of these issues, I'm not sure that this asset should be advertised for GMS2 when it seems that it was created in and for GMS1.4.  I'd very much appreciate some assistance though.