Resuggest based on Xergoyf's comments:

I think it is pretty clear that the mp market does not support the regular item market for this item, as the highest pure sale is 33 with this many sales. I would probably just go 28 - 34 and exclude the mp sales, including 34 as the high-end instead of something lower somewhat supports the higher sales.

Past 30 days https://gladiator.tf/sales?item=Fountain%20of%20Delight%20Taunt:%20The%20Schadenfreude&at=2021-11-28T06:34:28.951Z

1 @ 28 keys 29.44 ref

1 @ 28 keys 29.88 ref

1 @ 28 keys 30.11 ref

1 @ 30 keys

Previous month https://gladiator.tf/sales?item=Fountain%20of%20Delight%20Taunt:%20The%20Schadenfreude&at=2021-10-28T06:34:28.951Z

1 @ 33 keys

Month before that https://gladiator.tf/sales?item=Fountain%20of%20Delight%20Taunt:%20The%20Schadenfreude&at=2021-09-28T06:34:28.951Z

2 @ 27 keys 24 ref

1 @ 27 keys 25 ref

2 @ 28 keys 1.22 ref

1 @ 28 keys 1.77 ref

1 @ 28 keys 2.22 ref

1 @ 31 keys 35 ref

https://marketplace.tf/items/tf2/463;5;u3005 (Sep 14 - )

38k

38k

38k

38k

38k

38k

37k

37k

37k

37/38k

https://mannco.store/item/440-fountain-of-delight-unusual-taunt-the-schadenfreude (Nov 18)

34k

Buyers 28.5k+, sellers 29.5-39k https://gladiator.tf/listings/61a31d4506b9247d583c30bb

28-34 as suggested.