Although the meaning is “evaluate,” the meaning explanation and reading explanation both use the phrase “say your peace” several times, which is incorrect English. The correct version is “say your piece.”
If it were only one occurrence, I would normally just pass it off as a typo, but it appears, incorrectly, every time (four times). I think this could be particularly problematic for non-native English speakers (and even some native English speakers, I’m sure) who might not know the difference, and then who may inadvertently learn incorrect English as a result.
Of course, the second problem is the fact that 平 means “peace” in the first place… so, in order to fix the error in the idiom, you’ll have to do away with the idiom entirely and come up with a different way to explain 評 as “evaluate.”
Some ideas:
• saying your evaluation of something, which causes an uproar (of angry “Hey-yo!” protests?), so you have to keep the peace
• you have nothing to say in/about the/as an evaluation, so you hold your peace
As you can see, “keep the peace” and “hold your peace” would be correct, usable idioms.
If you’d like to adopt either of those ideas, feel free to do so. And as always, thank you for everything you do for us WKers. 
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