Scene producer font change

General
1

Hi,
I would like to change by an external variable the size, the font or the color of the font included in a scene producer,
with a variable of this type:

<variable type = "number" public = "true" id = "font"> LiberationSans-Bold </ variable>
<variable type = "number" public = "true" id = "size"> 20 </ variable>
<variable type = "number" public = "true" id = "color"> black </ variable>

do you have an idea ?

<layer id="text">
  <producer>[TEXT] "" 0 0 size 18 color black font LiberationSans-Bold</producer>
  <x>${variable.current_text_pos + variable.animation_pos_x}</x>
  <y>${layer.plate.y + layer.plate.height - f2}</y>
  <parameters>
    <text>${text}</text>
  </parameters>
</layer>
2

No solution ?