When using Static Orb (SO) with Fusion Blast (FuB), your next X number of uses of Lightning Blast (LB) chain 2 additional times, where X is the number of points in FB. That seems to work as intended.
When using LB with Focal Blast (FoB), it does not chain, but instead deal 30% more damage for each time it would have chained. So, if you use SO with FuB level X, I expect the next X uses of LB to deal 60% more damage while I have FoB allocated.
What I see instead is that the next X-1 uses of LB deal 60% more damage. That seems to be consistent at all levels of FuB (at level 1, no LB with more damage, at level 2, 1 LB with more damage, up to level 5, 4 LB with more damage)