Built-in enums are new and a bit of a funny matter because they are defined in fnames like this

AudioEffectType#*

??AudioEffectType
Bitcrusher?#*
Delay?#*
Gain?#*
HPF2?#*
LPF2?#*
Reverb1?#*
Tremolo?#*
PeakEQ?#*
HiShelf?#*
LoShelf?#*
EQ?#*
Compressor?#*

But you can do this for now in the end of obj_gmlive’s Create event

var e:live_enum = live_enum_create_builtin("AudioEffectType");
e.h_add("Bitcrusher", AudioEffectType.Bitcrusher);
// ... more h_add() calls for enum items