I just got the whisper catalyst cuz I figure it's important before its gone however I ran through the heroic whisper mission after unlocking the catalyst and got all 6 chests, and my catalyst only got to 12%.
The chests will only provide a small increase.
It's defeating the bosses at the end that gives you the biggest increase.
If you only have 12% sounds like you only collected the chests, including the Oracle one.
If I recall - completing the heroic missions, including the 6 chests, should have netted you around 30% to 35%