In the series towards the end the seem capable of getting Kamjin ship in ship space. By Macross Plus one of them is an engineer who designs VF for General Galaxy. Even before the their full contact with human they showed signs of patching up. Prior to contact they did the best they could and used the factorys for the rest of their needs. Being technological retard as a generic trait was something of Robotech and the Robotech RPG. The origin of the Zentradi like battle suit in Macross Plus was never revealed. There is a likely hood that the design was just as old as all the other Zentradi mecha but it just wasn't encounter by the UNS during the SW1. With 1000 Zentradi fleets flying around there is a chance that some will have different variants of mecha,