currently, it's a mojo's choice whether to throw a MojoExecutionException or MojoFailureException and stop the build when something comes up during its own execution. In many cases, mojos choose to output ERROR or WARNING messages, but these often are drowned in the sheer volume of INFO output to the console.
Look into modifying the default mojo Log class to record anything above INFO for recovery later by the CLI reporter methods, so ERROR and WARNING output can be added to the summary for that project.
Possibly even a good idea to adjust the summary pronouncement (BUILD SUCCESSFUL, BUILD FAILED) to reflect the presence of this sort of output:
BUILD SUCCESSFUL, with warnings
or something similar.