This issue is related to translations on workflow rules.
The text that you see on a workflow rule is taken from a translation so you can translate the rule names into different languages.
When you create a workflow rule, it creates the translation - it uses the text you enter in as the CODE for the translation AND it puts that text in as the translation as well.
If you edit a workflow rule, when you change the name, you are not actually changing the translation, you are just changing the CODE of the translation. So it still appears incorrect.
1. create 2 custom entities with workflow
2. create some workflow rule for 1 of them - for example "approve"
3. create workflow rule for entity 2 like "approve me" and save it
4. rename "approve me" to "approve", it should remain as "approve me" in UI but in db it is "approve"
If you want to actually change the translation you have to go to: Administration -> Customisation -> Translations and find the translation for that rule by searching with Caption Family = 'WorkflowRules' and the Caption Code is your workflow rule name - when you change the translations there, then you will see the new rule names.
Development are aware of this difficulty around workflow rule translations and there may be enhancements in the future