Hi,
to all waiting for an update(takes about 5 minutes or so):
Go to your workshow folder inside your steam folder e.g. *\SteamLibrary\steamapps\workshop\content\281990\692855172 (that 281990 shoudl be stellaris id, the 69x the mods id)

Prepare your mod:
unzip the folder into a new folder inside the stellaris mod folder:
e.g. Users\<name>\Documents\Paradox Interactive\Stellaris\mod\extDev

create a .mod file in the games mod folder ( Users\<name>\Documents\Paradox Interactive\Stellaris\mod)
e.g. in our case extDev.mod and copy this into it:
name="extDev"
path="mod/extDev"
tags={
"Balance"
}
supported_version="1.9.1"


now open the file orbital_bombardment.txt in contained in <yourMod>\events
Open the vanilla file in steam\steamapps\Stellaris\events as well

1)In the mod-file remove the content until you reach the "namespace = exterminatus"
2)copy the entire content of the vanilla file into this file (replacing the removed content)
3)add orbital_bombardment = armageddon to the two or cases in the namespace = exterminatus

e.g.


trigger = {
fortification_health = 0
OR = {
orbital_bombardment = full
orbital_bombardment = limited
}
FROM = { is_ai = no }
FROM = { has_edict = exterminatus_weapons_allowed }
is_ringworld = no
}

becomes

trigger = {
fortification_health = 0
OR = {
orbital_bombardment = full
orbital_bombardment = limited
orbital_bombardment = armageddon
}
FROM = { is_ai = no }
FROM = { has_edict = exterminatus_weapons_allowed }
is_ringworld = no
}

4)Load your mod and bring the emperors justice

ps.: I did only test the wipeout triggers, so yes you can again cleanse planets. I did not check whether the events for the better types trigger as well.
ps2.: exterminatus war goal works