It isn’t possible for someone to consistently assert “X is true, but X doesn’t seem true to me”. And it isn’t possible for someone to consistently assert “X seems true to me, but X is false”. [1] So even though “seems to me” and “is” are not logically the same thing, no human being can separate them and we have no need for a special word to make it convenient to separate them.
[1] Of course they can assert that if we use a secondary meaning for ‘seems’ such as “superficially appears to be”, but that’s not the meaning of ‘seems’ in question here.
It isn’t possible for someone to consistently assert “X is true, but X doesn’t seem true to me”. And it isn’t possible for someone to consistently assert “X seems true to me, but X is false”. [1] So even though “seems to me” and “is” are not logically the same thing, no human being can separate them and we have no need for a special word to make it convenient to separate them.
[1] Of course they can assert that if we use a secondary meaning for ‘seems’ such as “superficially appears to be”, but that’s not the meaning of ‘seems’ in question here.