It is highly recommended to get in the habit of properly unregistering and re-registering DLL files.

Yes you would probably not experience any issue with KiXforms DLL by just overwriting it, but the preferred method is to run

Unregister
regsvr32 /u kixforms.dll

Register
regsvr32 kixforms.dll

That can be run from the RUN command on the start menu so only takes less then a second.

The updated version of Inquisitor2.kix is located here

http://www.wheelerfam.com/Documents/Inquisitor2.kix

The updated version of KiXforms is located here
http://www.kixforms.com/assets/index.htm