wintermute

unless im misunderstanding the problem, I don't think OP could get the fortuna kitguns given their current predicament.

Though, a sporelacer secondary would rip

My understanding is that certain frame abilities, such as Roar, Eclipse and Xata's Whisper are tagged as "damage boosting" abilities, and can only be subsumed onto other damage boosting abilities, specifically to prevent that interaction.

source info can be found at this section of the wiki: https://warframe.fandom.com/wiki/Helminth#Injecting_and_Replacing_Abilities

As others might have explained, the "event" which lasts a couple weeks will grant access to the Kullervo prison island regardless of the current spiral. After the event is over, and on normal runs, the hold will only show up on certain spirals and not others, similar to Archarbor