Related to Invalid NS API function name in debug logs - Serious bug or just logging bug?... I didn't want this to get buried as a reply to that topic so I'm starting this one.
I've been struggling with an Item Fulfillment for many hours. Opened a NetSuite support case (because the Celigo error message suggests as much) and finally met with the brilliant, esteemed @davidgollom 
So... the error from the Import step was:
Failed to create, update/transform record because null Possible reasons include > Something went wrong on NetSuite side. > You might have specified an invalid field value for a field. > You may have submitted an invalid record. Please consult NetSuite Support with NLAPI calls obtained from NetSuite Connection Debugger.
Dave asked "Did you try a 1.0 version?? Shouldn't still need to do that, but in these weird cases it sometimes works." Well, Dave... it does work and I would love to know why!
Celigo, can you help us/me understand why this is still needed? I know this "workaround" has been a possible solution for years, here's a thread from August 2023. Luckily the SuiteApp 1.0 version works and we don't need to use the SuiteBundler version. Is there a real NetSuite difference in the APIs that make this workaround a valid option, or is this a case of "we just haven't fixed it yet"?