I have Romanoff oak parquetry on the floors, new one shown here with 160mm tiles. The old parquetry in the pictures has become a bit dark that I want to polish besides filling the hole with new parquetry tiles. The photos below show the hole, filling the earlier kitchen island, which I now want to have as open space.

where you can see that current parquetry is perfectly aligned as shown by laser, also in vertical way. The size of the area is 2m2, taking 80 new tiles (4 x 20), surrounded by already installed parquetry. The exact size for the backer board is 0.64m x 3.2m (=40.16 x 200.16) i.e. 2.048m2.

I have identified the following steps:

1. straighten up the underlying concrete with a spirit level and sanding/grinding? How coarse does the underlying floor stay for the glue to attach to it later?

2. installation of some other type of floor between the cement and the parquetry: install noise-cancellation floor if needed

3. using 2-phase glue to install parquetry to the extra layer

4. sand the installed floor and the old floor to make it on the same level

How to renovate the old parquetry with a hole in the old parquetry?