You probably got the same care sheet I and others have received. My goliathus pupated at 34.7 grams, I followed all instructions.
There are some articles you might want to look at- insect-collection.com/invertebrate-caresheet/journal-of-a-goliathus-breeder
this other one is good as well- scarabsnewsletter.com/scarabs_78.pdf
There is not a lot of information in comparison to other beetle species.
Next time I try this species, I'm going to supplement with moist food, like pet treats, any flavor, it doesn't matter.
I used the premium koi pellets and fed mine as much as it would eat, sometimes 3 times a day I'd feed it, and cleaned the substrate every
3 days or so. I used the red clay, and the grub dug down 8" and formed a cocoon, it grew very quickly, I got the grub on 10-1, and it stopped eating
(early) on 12-12. Other people have had this issue, You can read the articles, make conclusions. Next time I do this, besides the moist food, I'm
going to add some normal beetle substrate as well with the recommended coconut fiber..
Good luck! The so called "wandering phase" is highly unlikely in nature, picture a 90 gram protein log crawling around topside...it'd last 1 to 2 minutes.