After thinking about it more, I think what Tien has described could also be upacāra samādhi.
Unlike jhānās (which are limited in number), samādhi can be many varieties. There can even be miccā samādhi.
– When one gets fully absorbed in an ārammana (topic), one may not hear, see, etc.
– A simple example is when one is fully absorbed in reading a book, one may not hear, see, etc.
This is discussed in, “What is Samadhi? – Three Kinds of Mindfulness“.
Magga phala and jhāna are two different things. I think Chrisitian is talking about jhanas. It is not necessary to get to jhana to attain magga phala. We all have attained jhana in previous lives.
– It is easy to attain jhana for those who had cultivated them in recent previous lives or were born in brahma realms in recent previous lives.
– One can attain magga phala without jhana (via upacara samadhi).
– One who has anaraiya jhana does not have a magga phala.
– One with magga phala may or may not be able to get to a jhana easily.
More details at: “Samādhi, Jhāna (Dhyāna), Magga Phala“.
Thanks to y not for the reference.