A transhumanist colonist has a bionic arm, but no associated mood buff is apparent.
Build 1978, no mods.
https://imgur.com/a/x6SPEY5
They changed that.
Without bionic's you are geting a mood malus,
with 1 bionic no mood change and only with 2 and more you are geting a mood boni.
It is maybe bad explained at the trait description but i think it is working like intend.
Ah, righto then.
Then maybe a suggestion:
No bionics, negative mood buff
1 bionic, mood buff that's either zero or very small, +2 or something - this buff would be worded to suggest more implants would make him even happier "nice, i got a bionic, but man i wish i had MORE!"
2 bionics, bigger buff