Playing a bard, currently lvl 5 and in the bandit camp. Just used countersong for the first time. It appears that the bard's countersong feat is using the powered up countersong you gave to the Dissonant Chord prestige class. As I understand it, for a regular bard, countersong should give spell resistance 10+bard lvl and should go away after one spell is cast upon the individual with countersong.
So my lvl 5 bard should receive 15 spell resistance and the countersong should go away after one spell hits me. However, when I used countersong, it correctly worked on myself, but it gave me 20 spell resistance (I have a 20 charisma, so I was getting the +5 from my charisma modifier). It also lasted for several rounds. In other words, it behaved exactly as it says it does for the Dissonant Chord prestige class.
I tested this by letting a bandit mage use a wand of lightning on me over and over again. In the combat log, every time I was hit by the spell, my spell resistance from countersong attempted to resist it. I was hit 4 times the the lightning spell. I resisted twice and failed twice.
Thought you should know as I don't think you intended for a regular bard's countersong to work as such.
I have no other files in my override that conflict with yours or that alter spells or feats in any way.