For those hard climbing sessions, consider them like strength training sessions. The way I like to allocate TSS for strength/hard climbing sessions is based on how long it takes to recover. As typical hard strength session is going to need 48-72 hours to recovery from and I usually give these 80TSS/hr. A hard ME strength session or anaerobic endurance climbing session I call 100-200 depending on recovery time.
Just be consistent on how you track it.