With a combination of scripts and OXCE armor parameters this is certainly possible to do in a mod, but who wants to make chryssalids less scary?
Could you please explain how to do it?
Regarding the concern that it would make them less scary — I think that giving them "isLeeroyJenkins" more than makes up for it. Of course, I haven't had the chance to test the combination of these two changes, since I don't know how to make this delay, I only tested isLeeroyJenkins alone. But if I am not mistaken, it makes them like almost 5 times scarier, so it would more than make up for the delay.
And I feel that the delay is necessary because if the Chryssalids had metabolism rate fast enough to develop from an egg to a fully grown organism in a second, then they must also have 100% health recovery, so that if they are not killed in one turn, they restore from 1 HP to full health by the next turn. And also make them only 20% vulnerable to all types of damage to reflect the fact that they regenerate almost more quickly than you can inflict it. For me, to have consistency they either have to have this high regeneration, or have a delay of hatching, at least three turns.
As I said, there are other ways to compensate for this delay. People who do not agree with it can stick with the original model, but for my personal installation I would very much like to make this change.
And gameplay-wise it would make the player prioritize dealing with the fresh zombies quickly. Currently you have to avoid killing them unless you have the firepower to deal with the hatched Chryssalid in the same turn. This change would force the player to make dealing with zombies quickly the first order of buziness. It would be especially nice in Snakeman-initiated terror missions by making the player hurry up because the quicker he acts, the less Chryssalids he have to face. Of course now you also have to hurry, to prevent zombification of civilians. But this delay would give an additional incentive to hurry and hunt the civilian zombies in the first several turns.