Wasalam
May Allah bless you.
The best thing would be to refer to the judgment made by Zoya or Islamicly. If they considered it to be shariah compliant then trust their judgments.
As to how much you should purify from any income received, then check how much of the haram income has been earned through this fund. If the haram income represents 5% of global income, then you will give away 5% from your earnings.
As for purifying the capital gains made, see the link below:
Kind regards