Hello @Kal_Lam,
Thanks for this answer !
The specific problem remaining is that the form heigth sometimes depends on users’ entries. For such dynamic forms, it’s important that WORDPRESS can fetch the actual heigth of the form’s content, in order to then render it correctly, where embedded.
I started a thread focusing on the issue ( Clarification on X-Frame-Options Impacting Iframe Height Calculation in WordPress Integration ) … but it doesn’t seem quite easy to fix.
Any hint or step-by-step advice would be much appreciated 
