You will be happy to know that Newagemugen was originally called Club Syndicate Xtreme:https://mugen.fandom.com/wiki/Newagemugen
Anyway, i was able to download the mediafire link and i tested it.
I watched the video too and i see the bug happening.
i was able to replicate it and It does the same for me.
I just realized you're using Winmugen not Mugen 1.1.
Also i forgot about syns screenpack how it had custom patches that broke some poorly coded characters. thats gonna be a tricky one. you may be up the proverbial sh*t creek with no paddle.
But here are some suggestions to try as a bare minimum:
Unpatch godakuma->open in fighter factory->click project tab->check errors->fix everything you possibly can. some will require research if you are unsure of the bugs like syntax errors and stuff.
2.duplicate values in animations or statenos or something
Something in the lash codes is inteferring with the shungokusatsu or the other move or the changestate.
you will need to look at all states and animations and IDs related to those 2 moves.
Its possible that something added in the cmd file by the lash.exe is conflicting with something related to those 2 moves. you will need to notepad deep dive on all the definitions and codes and statedef added by the patch and see if anything is using numbers that relate to those moves.
The other thing to try is to convert everything to mugen 1.1 and see if it still happens