Paragon Chat doesn't explicitly send sequence bits (awwww) it sends MOVs.
Which makes sense if you consider that the mapserver also does not send sequencer bits to the client; it only sends the resulting MOV (technically the index into sequencers.bin that the MOV exists at).
So Paragon Chat itself has to convert bits to MOVs. Being that I thought he was a genius, I figured he just did a look up against the sequencer data to compute the MOV and dynamically send that, but its possible Codewalker is only a miracle worker and had to hard code the MOVs Paragon Chat supported.
Paragon Chat has an armed and fully operational sequencer. I can't be 100% certain that it obeys all of the same semantics as the clientside one when it comes to edge cases like randomizing between same priority MOVs or when interrupts are checked, but so far it seems to be working close enough.
Bits COSTUMECHANGE LIGHTNING
It's failing to parse because LIGHTNING is not a valid sequencer state bit. Most of the bit names can be found by running a strings utility against bin/seqstatebits.bin from bin.pigg. The rest are hardcoded into CityOfHeroes.exe because they are bits that have special meaning to the engine and can be extracted from there.
You want EMOTE CCCHANGE LIGHTNINGROD ONE
You got lucky on HOWL that there was an existing MOV that happened to match the HOWL bit. The COSTUMECHANGE bit doesn't seem to be used as a sequencer requirement but rather is a special flag for some other purpose. From what I can tell, the sequencer itself asserts COSTUMECHANGE at the right moment during the animation as a signal to the engine that it should swap costumes then.
I'm fairly sure I posted a text dump of sequencers.bin at some point in the Icon forums to help people find and document emotes. It contains a mapping of MOVs to the state bits that are required to trigger them. I'm pretty busy right now but maybe somebody can dig around for it and link it here?