You can't change blue light to another color with a filter. The amber light has to be in the spectrum emitted by the lights to begin with. The filter just isolates it.
That's overly simplistic - you can use phosphors (and similar chemicals) to change the color of the light. The phosphors absorb light and emit light of different colors. Many daylight bulbs do this.
There's an interesting Wired article, about how teams at Philips struggled to come up with the optimum filter. IIRC, at some point they were using some type of gel to 'tint' the LED light to resemble an incandescent bulb.
Of course, nearly all of this has probably flown out the window, because the bulbs are so cheap now. (The Wired article was from over a decade ago.)
That was the article about the Switch bulbs if I remember correctly. I think the company went out of business. I have a couple of them and they work and look good, but are really heavy and I can't use them in certain applications that were only ever meant to hold up really light incandescents.