You should use the design type name 'Kamikaze Attack Ship' to match the AI's current usage.
You do not compile the file Script_AI_DesignCreation, please refer to the Wiki on which files actually get compiled and where they need to go:
http://wiki.spaceempires.net/index.p...t_Editing_(SEV)
(You may need to cut and paste link due to forum cutting off parenthesis)
In the end the one change you'll be making will only help out individual Kamikaze ships outside of fleets. The TF strategy will always overrule the design type strategy. For effective fleet usage of kamikaze ships, they need to be in a TF with the kamikaze strategy. I'll add this behavior in the next version of the mod.
AIs give Troop Transports a weapon to keep them together with the other warships when they are approaching a planet to capture it. It sometimes helps to avoid accidental glassings of the target or protect the troop transport.