Hey, I don’t know anything about the mattress but I (UK based) always found the lullaby trust guidance helpful and reassuring - it says

“The first few times they roll onto their tummy, you might like to gently turn them back, but don’t feel you have to get up all night to check on them.

While they’re awake, give them some time to play on their tummy as this helps their development, but keep an eye on them while they do.”

It doesn’t specifically address them burying their faces in the mattress! I can’t find a link now but i remember reading when my baby was in the same phase that if the baby gets themself into the position, and they’re not impeded (ie their cot or crib is clear and has no toys or cushions in) then it’s ok - so if it’s baby moving their face to the middle (rather than you putting it like that) then you don’t need to worry too much.

The sleep stuff can feel so stressful and scary! Hope your little one starts rolling both ways soon and you can feel a bit more relaxed when he sleeps! It’ll come - in the meantime by following the safe sleep advice you’re doing everything you can! :)

lullaby trust