The tin whistle I used in A Song of Adventure and A Legendary Song is "Tin Whistle by Ventus Winds". I also really love how expressive it can get with all the articulations there are.
About A Legendary Song, thank you very much for the advice. I also had some difficulties with the overall loudness of the sound; the drums would spike the true peak meter without really increasing the perceived loudness so that particular track would sound a bit lower than the others (to stay below -1 dB of true peak). I still have to find a solution for that.
And thank you so much for your detailed review ! Really glad to read you've enjoyed it.