Is it possible to have a tester read the results of a former transformer as the passing criteria

Can you provide a little more context? You can plug in the value of an attribute with @Value(AttributeName) (or through the drop-down menu) in both the Left Value and Right Value of your Tester. Is this what you mean? See the settings of the two testers in the screenshot below.

Or do you want to avoid having to manually change the name of the attribute thats Tested on? You could partly avoid this this by either setting the name of the output attribute of your transformer to a generic name, or by changing the name with e.g. the AttributeRenamer to a generic name. See the screenshot as well.

This would still mean you have to change the attribute names every time you switch your transformers. You could also make several workflows in the same workspace, where you guide your features to the correct one (maybe with an user attribute). This prevents you from having to change your workspace a lot. But this can of course mean you get a very large workspace, a small example is in the screenshot below.