Nothing says, warforged can or can not drink, eat, breath... so your adding rules that don't exist and taking player agency if that's not what they want...why?
I am not adding rules, as you say, it doesn't say they can't, the original question was "can they play wind instrument" The answer is yes. Anything beyond that to me is overthinking it. If you want to go nuts describing how they have these big assembly lines and are rolling theses things out like Model Ts and come up with a million little details of production go for it, this forum is all about discussion, but let's not pretend it isn't a dumb thing to argue about, it's all just silly fun.
I don't think its over thinking for players to describe their characters. I has happened in every campaign with every character I have ever had at my table by anyone. All I am saying it then a Player describes how they have x color skin , x eyes, they have x shape to their horns, and x properties to their tail.... the warforged player does the same thing... and if that warforged player says they have lips and bellows, then they have lips and bellows. If they say the don't , they don't. If they say they can't play in instrument because they have no lips. You can say its dumb to argue but its the discussion we are having. My point is the answer to "can they play wind instrument" is not a yes or no, it is "That depends on what the player making the character decides". That is always the right answer for player agency when it comes to character creation and their is no rule.
I write long and repetitive in an effort to be clear. I am also bad at examples. As a result it is common for people to skim my posts pull out the idea they think I mean or want to argue against or focus on my bad example instead of the point I am actually trying to make. I apologies for the confusion my failure to be clear and concise creates.
The original question wasn’t about player agency, it was a simple question. If you want to discuss agency go for it. If a player wants to say they are playing a Warforged with no lips go for it, but I would follow up such a description with “so they can’t speak?”