Ok after some tests in the lab, here’s what works and what don’t
In the cr. mp list everything works as expected basically. All cr. mp can follow-up with cr. mk and cannon spike or spiral arrow. However, cr.lk st.lp with trap on cr.mp does not work (on ryu at least), too much push back.
On the b. mp side, any traps with jab (cr. or not) works as expected but timing is really hard to confirm!
For light traps, unfortunately there is too much push back to make the link st. lp counter -> st. hp which is on block for some reason. Therefore, no clear damage can output from this. But, cr. mp cr. lp works as expected.
Now, I’ve fiddled with crossup lk which traps pretty easily on st. mp allowing cr. hp. This cr. hp is CA-cancelable and V-Trigger cancelable (with a cr. mk followup), so expect a ~350-400 damage from a st.mp trap
So here’s the list of clear confirmed 3f traps with a strong enough followup
 v-skill cr. mp (cr. mk or cr. hk)
 st. mp cr. mp (cr. mk or cr. hk)
 st. lp cr. mp (cr. mk or cr. hk)
 (cr.) lp b.mp (xx hk if you’re fast enough)
 cr. mp cr. lp (st. hp)
 crossup j. lk st. mp (cr. hp or cr. mk)
If you allow 4f traps for characters without a 3f light (birdie, dhalsim, fang, ken, bison, nash, zangief)
 st. lp st. mp (cr. hp or cr. mk)
 st. mp st. mp (cr. hp or cr. mk)
 v-skill st. mp (cr. hp or cr. mk)
 cr. mp cr. mp (cr. mk cr. hk)
[*] cr. lp cr. mp (cr. mk or cr. hk)
Other traps may exists but depends on the character. For instance, cr. lp cr. mp is a jab trap on ryu even thought it’s a 4f trap, but hurtbox of the jab against crouched cammy makes it alright.
@n0b34ts you can maybe put this two lists on top I think i’ll do a quick video tomorrow to showcase those traps.