Your charging BG was definitely in a possition where it could make a legal flank charge but without the LF in the way the charge would not have counted as a flank charge because it would have hit the front corner. The LF in the way would force your charging BG to drop a file back to make room and the charge would be a real flank charge.
The intercetion part is much easier. Interceptions can only be made by BGs that are not being charged (you were OK on this one) and where the chargers will cross the zone of interception or in this case 2MU directly in front of the BG wanting to intercept (in your example it looks like the charge goes nowhere near the ZOI of the rear BG.
Where an interception charge crosses the path of a charge the chargers must contact the interceping BG and if appropriate step forwards.
If you have a situation like this:
Where I are the interceptors and are more than their interception move behind the target of the charge T then I cannot intercept even though if it moved forwards its interception distance it would put it in a possition where the chargers C would step forwards into them. This is because the charge of C does not cross the ZoI of I.
If I was nearer T such that it could intercept past BG T then the interceptors could move past T forcing C to hit them as well at the initial target.