Working on my understanding of the LoS rules. Let's see if I get this right:
1. The LoS from all US units within the blue circle to the Japanese units in H8 would be degraded by the Light Jungle in hex H7. The US units in G3 (top left) and I3 both have a LoS to the Japanese units (albeit degraded) because the shadow created by the same-level hexes G4 and I4, respectively, only block their LoS to hexes G5, H5, and I5 but they have a LoS to all hexes south of these hexes.
2. The LoS of the US unit labeled "A" would also be degraded but from the Light Jungle in hex I6; while the LoS shadow is regularly only one hex, the fact that unit is one hex away from I6 extends this shadow by one hex, therefore also affecting the LoS to the Japanese units in H8. Hex H7 does NOT affect unit A's LoS since it's only on one side of a hex spine between H7 and I7.
3. The LoS of all the US units labeled "B" is not degraded, since they are on a higher level than the Level 1 Light Jungle in I6, thereby limiting the hex shadow of hex I6 to one hex, even though there are are two hexes between the units B and hex I6.