Manjaro xfce bengali font Problem solve. copy this file to (if directory not exist create one) ~/.config/fontconfig/conf.d/90-bn.conf

90-bn.conf

<fontconfig>
   <match target="pattern">
      <test name="lang" compare="contains">
         <string>bn</string>
      </test>
      <test qual="any" name="family">
         <string>sans-serif</string>
      </test>
      <edit name="family" mode="prepend" binding="strong">
         <string>Noto Sans Bengali</string>
      </edit>
   </match>
   <match target="pattern">
      <test name="lang" compare="contains">
         <string>bn</string>
      </test>
      <test qual="any" name="family">
         <string>serif</string>
      </test>
      <edit name="family" mode="prepend" binding="strong">
         <string>Noto Sans Bengali</string>
      </edit>
   </match>
</fontconfig>