18-20" seat height with cushion for a 28-30" high table. That bench seems high with cushion. A comfortable cushion like latex foam with a small back will help. 28" tabletop height is more casual. Closer to card table height. With the bench lowered if necessary and a correct table I'd keep the bench seating. The right facetted table may need to have a custom dimensioned top. It doesn't need to be a full circle. A flat side is better. That could make it cozier. Like a boat salon.

Dan 1888 has good suggestions.
Everything depends on how you intend to use the space.
Is the current sitting height comfortable?
Are the built ins actually storage with lift tops?
Would you prefer that space as a dining spot with movable chairs and a normal height table?
Does a cosy area with a small round table and two cushy chairs appeal?
How would you utilise the electric outlets?
So much depends on your personal preference.
Consider all factors before spending time and money on alterations or demo.
Please show us how you have updated this already pleasant space.

Could you post a floor plan to get more ideas? It’s hard to get a sense of how anything is connected from the two pics shared.

I'd get rid of the built in bench and replace with a table and chairs to soften the cabin feel.

is it just one open room for kitchen dining and relaxation around the fireplace?

I would not remove the bench. If
you do consider the floor.

Add a round table to the area and go from there. Maybe have someone lower them. Check height when table is added

So how does the nook relate to the reest of the cabin A to scale floor plan is a must so we get to understand the layout of the whole not one bit ata time .The cabin looks pretty modern so might be easier to get rid of the benches that to try to make them work I dislikre that type of seating for any table

Built-in benches can be uncomfortable since there is really no back to lean against. The nook might be more comfortable and, therefore, more usable with chairs and a table instead.

Depends on if there is another space to dine comfortably? Do you know for sure the floor runs under the benches? Like already said, a floor plan would help and lots more pictures. Cute space - congratulations!