Oh, I know what this is.
The "insert word here" parts are tied to species class (humanoid, fungoid, avian and so on) in localisation files. Since your primary species changed classification to synthetic, it must be that the game wants to use synthetic-specific insults and such but it can't because they are not defined there, probably because they were never intended to be playable until now.
A lot about the synthetic ascension looks like it wasn't well thought out. Desperately needs at the very, very least a quality of life pass (auto-build, the ability to convert new pops after the original ascension, probably other things) and bugfixing. And customisable portraits. I won't condemn my pretty species to an eternal existence as generic toaster heads, that's just evil.
Update: Actually, I just checked and need to correct myself. Localisation DOES have definitions (name_lists_l_english.yml) for Synth-specific epithets... which makes it even weirder. I have noooo idea why it wouldn't work... Here's an excerpt:
Code:
#ROBOT: "Robot"
ROBOT_desc: "Species Class has no effect on your Empire, but Robot-class Species may consider other Robots to be less alien than other Species Classes."
ROBOT_plural: "Robots"
ROBOT_insult_01: "tin can"
ROBOT_insult_plural_01: "toasters"
ROBOT_compliment_01: "elegant automaton"
ROBOT_compliment_plural_01: "technological marvels"
ROBOT_spawn: "immature processing unit"
ROBOT_spawn_plural: "young automata"
ROBOT_sound_01: "whirring"
ROBOT_sound_02: "clanging"
ROBOT_sound_03: "scraping"
ROBOT_sound_04: "beeping"
ROBOT_sound_05: "chattering"
ROBOT_organ: "motherboard"
ROBOT_mouth: "energy intake port"