The issue you are experiencing here is not related to At Ease or the newer version of ClarisWorks. You can test this by turning off At Ease using the At Ease Setup application and restarting. If the same failure occurs, then you have ruled out At Ease interfering with ClarisWorks' translators.
Since the ClarisWorks Translators folder has all the necessary translation files available, the issue is related to access and interaction with those files.
System 7.5 includes a control panel called Macintosh Easy Open (MEO), which builds a table of file types, applications, and the translators available to those applications that give them the ability to open different file types. When you double-click a file, the Finder checks with MEO to see what application it should use to to launch, or perhaps translate, a file.
Since you installed the new version of ClarisWorks, MEO now needs to update this table. This can be done by rebuilding the Desktop file of your Macintosh in the following way:
1. Make sure you have turned off At Ease using the At Ease Setup program.
2. Restart your Macintosh and hold down the Space Bar until the Extensions Manager control panel opens.
3. Use the pull down menu in the Extensions Manager to choose "All Off"
4. Scroll down to the Control Panels section of the Extensions Manager window and click the Macintosh Easy Open item to put a check mark by it.
5. Close the Extensions Manager window by clicking on the close box in the upper left corner.
6. Immediately hold down the Command (Apple) and Option keys until you see the dialog box, "Are you sure you want to rebuild the desktop file?"
7. Click Okay.
After the desktop rebuilds you can test to see if you have been successful by double clicking the file in question. Once you have determined everything is working normally, you can go back to the Extensions Manager and turn on all the extensions you usually use including At Ease. You need to restart to have the reactivated extensions load.
It is a good idea to rebuild the desktop file this way after installing any new software.