How to enable fake slant feature in kitty?

[0And1Story]

I'm trying to configure Chinese fonts in kitty. I prefer to use JetBrains Mono in English and Noto Sans CJK SC in Chinese.

To solve the font fallback, I use

<?xml version="1.0"?>
<!DOCTYPE fontconfig SYSTEM "urn:fontconfig:fonts.dtd">
<fontconfig>
    <match target="pattern">
        <test name="prgname" compare="eq">
            <string>kitty</string>
        </test>
        <edit mode="prepend" name="family">
            <string>Noto Sans CJK SC</string>
        </edit>
    </match>
</fontconfig>

It works well in regular and bold fonts. But for CJK fonts, the font files rarely provide italic glyphs directly. Instead, they use fakeslant feature. Thus, I use this font config:

<?xml version="1.0"?>
<!DOCTYPE fontconfig SYSTEM "fonts.dtd">
<fontconfig>

  <!-- bold -->
  <match target="pattern">
    <test name="family"><string>Noto Sans CJK SC</string></test>
    <test name="weight" compare="more_eq"><const>bold</const></test>
    <edit name="family" mode="assign"><string>Noto Sans CJK SC</string></edit>
    <edit name="style" mode="assign"><string>Bold</string></edit>
  </match>

  <!-- italic (fake slant) -->
  <match target="font">
    <test name="family"><string>Noto Sans CJK SC</string></test>
    <test name="slant" compare="more_eq"><const>italic</const></test>
    <edit name="matrix" mode="assign">
      <matrix>
        <double>1</double><double>0.2</double>
        <double>0</double><double>1</double>
      </matrix>
    </edit>
    <edit name="slant" mode="assign"><const>italic</const></edit>
    <edit name="embeddedbitmap" mode="assign"><bool>false</bool></edit>
  </match>

</fontconfig>

$ fc-match "Noto Sans CJK SC:slant=italic" matrix
:matrix=1 0.2 0 1

I am sure that the configuration take effects, but it seems that kitty does not support this feature.

$ echo -e "\033[3m斜体中文测试 Italic\033[0m"
斜体中文测试 Italic

[43.511] U+659c italic using previous fallback font at index: 0
[43.513] U+4f53 italic using previous fallback font at index: 0
[43.515] U+4e2d italic using previous fallback font at index: 0
[43.516] U+6587 italic using previous fallback font at index: 0
[43.517] U+6d4b italic using previous fallback font at index: 0
[43.519] U+8bd5 italic using previous fallback font at index: 0

It fallbacks to Noto Sans CJK SC directly. I wonder if there is an approach to achieve my expected effects.

(Well, I know that fake slant is not a good feature in font designing, but it is special and important in CJK fonts.)