Electronic – Can capacitors in speakers (Yamaha) be replaced by slightly different ones

You are totally correct, if you don't connect the private wire of the third capacitor (or short it to the common) it won't have any effect.

I only looked at one of your proposed parts, the Murata LLL153C80G105ME21. I compared it with a same-value part in a larger package (GRM21BR71E105KA99#, 0805 size), the key improvement is in the available voltage rating. The 0204 part is rated for 4 V, while the 0805 part is rated for 25 V.

Even if your application only applies 4 V to the cap, take note of the capacitance change with applied voltage charts. The value of the 0204 part will be reduced to a bit above 30% of nominal (e.g. 0.3 uF instead of 1 uF) with 4 V applied. The 0805 part will still be at 95% of its nominal value with 4 V applied, and only loses about 45% of its value at 25 V applied.

So the smaller part can be used if you can accept its reduced temperature range, but its value will be reduced to just a bit more than the 0.1 uF value that has been typically recommended for use as the near-chip bypass capacitor over the past decade or so. If you really want 1.0 uF of bypassing, you'll still have add some larger parts in parallel with the suggested 0204 part.

On the other hand, if you can live with the low WV rating and you use this part in place of the "traditional" 0.1 uF 0402 part (in parallel with additional larger-value caps), you will gain a 3 - 4x increase in effective capacitance, so that is a substantial improvement.

Also, in a high-reliability application, you may want to use a package at least one size up from the minimum needed for the capacitor value and WV you are using. The smallest available size is pushing the limits of what the manufacturers can do, and can have reliability issues.