For the past few years I've become aware of the addition of "as to" in sentences. So far, I haven't figured out the reason or the need. For example, in a novel I saw the two words used twice on the same page.
1. He declined to comment as to what actions the council might take.
2. Neither commented as to whether the company would be part of the effort.
Delete the two words and read the examples. They make good sense. Because people use them often, doesn't make them useful.
1. He declined to comment which actions the council might take. (I changed what to which.)
2. Neither commented whether the company would be part of the effort.
(FYI. My wife would add on after comment and commented. I didn't see the need for the additional word, but you may.)
Every word in a sentence needs to justify itself.