Unless there's some nuance I'm missing, I think you're reading too much into the word "accent".
Especially because the codepoint is actually called "Combining Ogonek".
And for anyone writing in Cyrillic, it's actually more accurate to use the combining form, even as its own letter, because the only precomposed form technically uses a latin A.
But my main point is that I do not think there is supposed to be any semantic difference in Unicode based on whether you use precomposed or decomposed code points.
Especially because the codepoint is actually called "Combining Ogonek".
And for anyone writing in Cyrillic, it's actually more accurate to use the combining form, even as its own letter, because the only precomposed form technically uses a latin A.
But my main point is that I do not think there is supposed to be any semantic difference in Unicode based on whether you use precomposed or decomposed code points.