In Rocksmith 1 customs, there were 4 known events (B0, B1, E1 and E3) that could be used to sound the in-game metronome or alter the crowd's level of enthusiasm, but that was pretty much it.

 

Are there any events that are used in Rocksmith 2014 (aside from perhaps the metronome)?

I could only say I tried using the crowd level event in EoF and it didn't have any effect of in-game. Apart from this, I don't know the answer to your question.

I could have sworn the toolkit's metronome track feature uses the metronome events, but it's not something I've tried.

Just opened up the heartshapedbox file (on disk) and here are some events:

 

<events count="17">
    <event time="10" code="e1" />
    <event time="10" code="B0" />
    <event time="10.651" code="B1" />
    <event time="11.303" code="B1" />
    <event time="11.954" code="B1" />
    <event time="12.606" code="dna_riff" />
    <event time="13.58" code="E3" />
    <event time="16.156" code="E13" />
    <event time="58.695" code="tone_b" />
    <event time="99.516" code="tone_a" />
    <event time="135.609" code="tone_b" />
    <event time="176.369" code="dna_solo" />
    <event time="190.455" code="tone_a" />
    <event time="195.422" code="dna_riff" />
    <event time="230.832" code="tone_b" />
    <event time="280.889" code="D3" />
    <event time="284.335" code="E13" />
  </events>

Metronome event are used, if i remember correctly the other two event does work in RS2014 but i've never tried it myself (i was just told it did change the crowd behavior)

I don't think anybody ever discovered what the D# events were all about. Kind of odd about the phrase/tone named events, I wonder if those are tied to scripts or something to do in-game effects.