You'd be wasting your time contacting the councillors' office for this.
If you have a noise issue email
311@toronto.ca. If this is a recurring problem provide some information on that matter. Describe the nature of the disturbance, the time it occurres at and how it is affecting you in your home.
An initial straight-up noise complaint, meaning one in which the allegation is that the level of noise is not permitted at all or not permitted after a certain time, should certainly go to 311/By-law first. Though, no harm copying the Councillor on that.
However, if the complaint is over a legal/permitted level of noise, for an outdoor market, where music is permitted, then the matter is squarely political in that this is on City land, and the market is tenant of the City.
The City, politically, can exercise different influence as landlord from that which by-law can apply, additional to that was the question of whether this use remains appropriate, noting that it has long been promised to the Community as a park.
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For my part, I lack any vested interest here, I'm not an area resident, and while I haven't noticed the noise being unreasonable when passing by or through, I am just passing by or through.
I like the idea of Stakt, but at some point the City does need to honour the original plan here, or formally abandon it and explain why.
Also, though I like the idea of Stakt, I've overall been underwhelmed by the businesses in it when passing through, there have been a couple of good ones through the years......but, overall......meh.