All beliefs even coherentism rest on some degrees of foundation.
There is strong and weak foundationalism and its continuum.
As such, explaining the context is critical.
The philosophical realist is also an empirical idealist.
Don't simply counter when you are have not understood [not necessary agree with] Kant's CPR thoroughly.
Kant in CPR wrote: [A369]To this [Transcendental] Idealism there is opposed a Transcendental Realism which regards Time and Space as something Given in-themselves, independently of our Sensibility.
The Transcendental Realist thus interprets Outer Appearances (their Reality being taken as granted) as Things-in-Themselves,
which exist independently of us and of our Sensibility, and
which are therefore Outside us
the phrase 'outside us' being interpreted in conformity with Pure Concepts of Understanding [Categories].
It is, in fact, this Transcendental Realist who afterwards plays the part of Empirical Idealist.
After wrongly supposing that Objects of the Senses, if they are to be External, must have an Existence-by-themselves, and independently of the Senses,
he [the Transcendental Realist] finds that, judged from this point of view [Transcendental Realism], all our sensuous Representations are inadequate to establish their Reality.
The transcendent realist aka philosophical realist believe a thing [noumenon aka thing-in-itself] exists absolutely mind-independently as real, i.e. it exists regardless whether there are humans or not.
To the transcendental/philosophical realist, this noumenon exists as real
beyond the empirical.
Idealism in philosophy,....... that reality is entirely a mental .. ; ........."
What is idealism is confined to the mind.
Thus as far as the transcendent realist aka philosophical realist, whatever is empirically is within his mind.
As such, the transcendent realist aka philosophical realist is also an empirical idealist; empirical wise, he is an empirical idealist.