The skill challenge has begun. For this skill challenge, the party needs at least one stealth success and one survival success per round to keep from being seen or leave signs to be seen by hobgoblins.
For skill variance between the five of you, you can't gain more than one success in a skill as a group per round. Urki, Kildrak, and Feng still have actions for this round. Applicable skills could include Stealth, Survival, Athletics, Nature, Perception, or anything else that you can make useful. If someone fails at a skill, another party member can try for a success in that skill. If a success has already been rolled in a particular skill, you can use a second success in the same round to give advantage to a party member on that skill in the next round.
Since Cassandra already got stealth, Ai Shan wouldn't have had too. If he had known about the survial roll he would have rolled survival so you have the choice of keeping it as a stealth roll to give advantage to a party member on stealth in the next round or change it to survival. We'll keep the 19 so my guess is that you'll switch to Survival and just move forward saying that requirement for this round has been filled.