I was trying to test a web service ... facing error while selecting the service

I mean the ACHTypes?

Yes.. if I change CDT ACHTypes to ACHTypess in wsdl and save my local wsdl copy and then loads the service in Appian .. then it works but in real time i can't change ACHTypes to ACHTypess

So Appian is having a reference of CDT ACHTypes and giving the error if i don't change CDT in WSDL
Attached error screen !

How to Overwrite ACHTypes which Appian is looking for

This proves this data type is marked as IMPORTING in the data types cache in the Process Design engine (this is the answer to your question about where this is cached). This will sound repetitive but I suggest you use approach B) I mentioned above which is wait 2 hrs after the restart of the app server after performing step #1 (since you have been trying so many times it could be you're re-introducing the issue , you better wait the two hours without trying to use that WSDL)

Just as an FYI, that's how we've solved this in the past several times.

Okay Edurado i can try the same on my local instance as suggested above but what about the cloud instance, which i can't restart ...

So can i say Appian can only load the Enums CDT/Types the very first time and but not after if there is any change in interface ( will hold a reference for future imports )
if we don't use Enums in web service schema declaration .. the error can be resolved .?. as I can see Enums CDT's are creating a mess ...
Please suggest

For the Cloud instance give it the two hours without restarting.

Looking a the symptoms it seems that the internal creation of the CDT was abruptly interrupted and not precisely related to the type of CDTs, but let's wait for the result of testing in your local instance in two more hours to confirm.

okay will wait ..

Eduardo .. i tried again but no luck ..
I have sent the local wsdl copy to your mail

Eduardo - It seems if Enums Types are defined schema for web service and if I have to reload the service in Appian ( because of some web service interface changes after deleting all earlier references for web services CDT's ) .. the Appian fails to load the Enum Types CDT again ... as it stores the earlier Enums references in engine ..

Please confirm or do i need to raise a Support Ticket