Or you can just put in description: Bounty tokens, amount: not known, the date: should be paid after ICO or not known, and so on. I did like this.
Or you can just count the exact amount because it's known that there were total 3M tokens available for bounty, for example 20% for that was reserved for translation = 600000 tokens, and that would be divided by number of all stakes for translations (28). Time that with the stakes you got. That makes 21428.57 env tokens for a translation.
And maybe put the spreadsheet and the bounty announcement in references.