Now, it may be so, but this apparent discrepancy in the Suttas may as well be only on verbal level, and dissolve itself after making certain distinction.
So:
MN 29 sequence
attainment of virtue→
concentration →
knowledge and vision →
perpetual liberation
can be seen as a description in more general terms as it is stated in the training which Lord Buddha usually emphasised in Paranibbana Sutta, namely morality - concentration - wisdom or understanding. So this description seems to be quite obvious and natural, and cannot be wrong.
But sequence in MN 30
attainment of virtue→
concentration →
knowledge and vision →
jhānas →
the cessation of perception and feeling and destruction of taints
goes into details, and describes things just from different angle.
Sutta AN VI,68 says:
‘“One not delighting in solitude could grasp the sign of the mind (cittassa nimittam)”: such a state is not to be found. “One not grasping the sign of the mind could be fulfilled in right view”: such a state is not to be found. “One not having fulfilled right view could be fulfilled in right concentration”: such a state is not to be found. “One not having fulfilled right concentration could abandon the fetters”: such a state is not to be found. “One not having abandoned the fetters could realize extinction”: such a state is not to be found.’
So here grasp the sign of the mind as I see it, can be classified as attainment of concentration and it is a middle way in dialectic: is concentration needed for sotapatti? And based on this Sutta we may say that: yes it is needed, but not a full jhana. So there is no mystery in the following sequence
grasping the sign of the mind →
right view→
jhānas →
And so on.
PS
I am aware that there is line of thinking: “sotapanna has a right view, but right view in noble eightfold path means jhānas, therefore sotapanna has an access to jhānas”, but again it is logical only on a crude verbal level and it doesn’t take into account that sotapnna is not free from desire and ill will, which are main obstacles in attainments of jhānas.
So in fact it is the task of sotapnna to develop jhānas and rise to the state of non-returner.