Hi Becky, I had the same struggle since I love Da’an Forest Park.
Usually when I visit there for relaxing or exerting, i often stop events happening out-the-blue at the stage/concert area of the park.
May I ask, what particular events are you interested in? Most band performances are all within the Taiwanese sites (in Chinese) and hardly reach the expat community stratosphere 🙁
The best I can find is the government site that my browser translates to English:
They’re obviously not that good, but it’s the best insight I’ve personally been able to get when seeing the odd concert prop up in the area… again, the band is usually sung all in Chinese but the concerts they list are usually good and lively.
other than that – I still view it as a random thing when I visit there to walk about and enjoy the weather…
hope that helps you ~