was Nestor a profi?

The Cronik of Nestor is considered to be a reliabel source
and, for his time, Nestor showed to be a very well informed
person about the thirbes, folks, and all what he wrote about.
There is a problem for me again with the valahians.
Nestor, who knew well the difference between several folks
tell us about the people living in Panonia as the Hungarian
came , that there are to find a romanized population called
"pastores romanus", slovaks and valahians.
The same information give us Anonymus, this one beeing
considered not so a reliable and serious source. But he did
the same, telling us about a romanized population called too,
pastores romanus and valahians.
The last one is the Simon de Keza, this one has wrotte the
last, more as 300 years after the events, and he say the same
thing, but, there are some places where Simon de Keza
identifies these pastoers romanus with valahians.Simon de Keza
is considered to be too, not so reliable having made a
mish-mash of legends and the events from the times he wrote
about.
From all 3, we have first a strange thing. They make a
difference among a romanized population, and an extra group,
group which is called valahian.
If Anonymus and Simon de Keza are not the ideal sources when
someone wants argue something, Nestor is suppoesd to be a
serious one.
This is why I ask myself, why did Nestor made this
difference?To make someone's headaches, for sure, not.
In this case we have two posibilities. He was wrong informed
or he told the true.
The first one , he was wrong infformed, is weak because in the
other cases it is proved he was right, so I dont see why he
would tell bed-stories about the valahians.
If he is not wrong, then the valahians were to see separated
from teh romanized group .
Which should have been at that time the criteria to
distinguish between a romanized population and a non romanized
one.? I am really, not so im clear what to belive from here,
so the question if Nestor was indeed a profi, or did he made a
mistake too, making a difference between valahians and the
pastores romanus?

regards

a. moeller