Hi,
For the meaning of error codes, let me refer to this Acados error status 2 on python interface - #2 by FreyJo
If the solver exits with nonzero status, non of the constraints are guaranteed to be satisfied.
Moreover, for SQP_RTI, the solver does not run until convergence and constraint satisfaction cannot be guarenteed in general.
I dont really know what you mean here.
The intermediate solutions are just the iterates of the SQP.
So, the iterates do not have to satisfy the constraints (also not the ones for the dynamics).
Best,
Jonathan