There are a couple of ways to go with this error message. Since the error mentions a version putting a limit on the identifier length, one option would be to locate this 'identifier length' and make it shorter. The following KB article should be able to help with this:
Using a TDC file often helps customers using Informix.
I might also seeing if there is a possibility to upgrade Informix, as this limitation may have been removed. Finally, as this is not a Tableau error, I would recommend searching google or going to the Informix site to see if there is any documentation from them on this error.
Hope this helps a bit!