You are getting a good clue in the error message already which makes this easier.
mapping/resample 100
The "mapping" external.
zexy/makesymbol Firmata-%s.%s
The "zexy" external.
comport $1 57600
The "comport" external. There is just a single object in this external, so "comport/comport" is redundant.
moocow/string2any 32 -1
The "moocow" external.
pddp/print
The "pddp" external.
I can't find some of these legacy libraries anywhere
If you are using Pd vanilla, each of these is available via Help->Find externals (aka the "deken" utility). If you are using the Pd "Documents directory," they will be downloaded into ~/Documents/Pd/externals which will already be added to your search paths, so everything but "comport" should load without having to do anything extra. For comport, you may need to add ~/Documents/Pd/externals/comport to your paths manually.
I checked and each of these is listed. As we have said in previous emails, *most* of the final library builds from Pd-extended were repackaged for deken. In many cases, there are newer versions available as well.