How does the return value true or false affects other plugins of the same group? Does it prevent other plugins from executing when returning false?
The outcome of the plugin output will affect overall process flow but not other plugins.
onContentBeforeSaveis a content event. If you return false, the article will not be saved and the error will be shown to the user.
onContentAfterTitlereturns a string value and it will be shown after article title.
However, the execution of other plugins will not be affected by this return value.