The reason for the error has been identified.

However nobody really addressed this question. Honestly I see a lot of things not necessarily wrong but far from optimal in here.

select * from [a number of table valued functions] You should avoid select * in code, it is fine for testing but NOT fine in production.

SplitString function is a potential for performance issue depending on how it is coded. Given the mass of cursors in the rest of this I would suspect this function is using a while loop?

c1 cursor. This looks like you could use STUFF instead of a cursor. More select *

In general I think you will find that in the future your naming conventions will cause you grief. They don't have anything that help identify what it is/does.

c2 cursor. This again looks like you could use STUFF instead of the cursor. More select *. the big change here would be to convert GetDataType from a scalar function to an iTVF.

c3 cursor. Another place you could use STUFF. More select *

c4 cursor. Another place you could use STUFF. More select *

Last but not least...you are wide open to sql injection attack. You generate a lot of dynamic sql and then execute it starting around line 154. What happens when somebody passes you 'MyTable; drop database tempdb;--'? Don't try that!!!

I don't think you need any cursors to do this and you need to read up a bit on sql injection and how to properly execute dynamic sql with parameters.