Floor flattener which will not damage sandstone sub floor

[NICPOM111]

Hi

I made the mistake of having my bathroom floor levelled, unfortunately this has left me with a 2cm step up at one side of the threshold. I will have to level an area outside the bathroom then cover with carpet.

Is there a floor flattener which will not damage the original Georgian flags underneath. They are part of an original larger hall which has been partioned off to create an ensuite bedroom so I want to make sueI don't do permanent damage.

We spent weeks chipping off old vinyl tiles which had a hard black adhesive/leveller underneath. This did not damage the floor at all and came off cleanly.

Problem is we have since ground the surface of the floor so it is probably more porous. Can I seal the floor before using the compound ?

Any advice greatly received.