Wandering trader are missing their sounds for drinking potions (not to be confused with MCPE-38340 because they have their own unique drinking sounds.) and disappearing/reappearing sounds.

Some sounds wandering traders are missing:

minecraft:entity.wandering_trader.drink_potion

minecraft:entity.wandering_trader.disappeared

minecraft:entity.wandering_trader.reapppeared

minecraft:entity.wandering_trader.drink_milk (MCPE-44605)

This can be heard in the Java Edition when using the /playsound command .Do note that the milk drinking feature for wandering traders isn't added yet although there is a sound for that and it is seperate from the issue MCPE-38340.