This is not related (I think) to your posting problem. Note that since some of your forms work fine, so it’s probably a coding glitch somewhere. Still searching you code for that.
The CSRF has been incorporated into CI. This is from the config file in 2.1.2-3
| Cross Site Request Forgery
| Enables a CSRF cookie token to be set. When set to TRUE, token will be
| checked on a submitted form. If you are accepting user data, it is strongly
| recommended CSRF protection be enabled.
Since your system is 2.0.2, it DOES NOT have CSRF protections built into the core files.
NOTE: this is probably NOT related to the POST problem you are having, and right now, you don’t want to dig into what it would take to add CSRF to your 2.0.2 code. I note it only because it is now part of the form helper library, added to fix the CSRF problem. If you feel you need CSRF protection, then a rewrite under at least Ver 2.1.x would be you best option… after we fix the POST problem.
You can do a web search on “Cross Site Request Forgery” and find out about the problem,