Not all Pali suttas are the words of the Buddha, which is why there are contradictions. In the Maha-parinibbana Sutta, this is addressed by the Four Great References.
The Karajakāya Sutta can appear a contradiction due to the Pali language, which often can be interpreted in two ways: (1) in mundane (lokiya) language, which will result in contradiction; and (2) in supramundane (lokuttara) language, which will not result in contradiction.
In mundane language, it seems the Karajakāya Sutta would make enlightenment impossible in a lifetime because the doer of bad kamma would keep being reborn in (an external) hell for each past unwholesome action.
However, in supramundane language, the results of kamma are experienced in the mind, such as the Buddha explained: "I recollected my manifold past dwellings, i.e., one birth, two... five, ten... fifty, a hundred, a thousand, a hundred thousand...There I had such a name, belonged to such a clan, had such an appearance. Such was my nutriment, such my experience of pleasure & pain..."
This said, the context of the Karajakāya Sutta is important. The section in the Anguttara Nikaya it is in are mundane (lokiya) teachings of morality rather than supramundane (lokuttara) teachings for enlightenment. For example, AN 10.217, which has the same teachings, is about the ten kinds of bad kamma that laypeople do.
Therefore, the Karajakāya Sutta appears to not be for enlightenment. It is mundane (lokiya) morality dhamma for laypeople or householders.
If we do not understand the principle of 'two kinds of right view' found in MN 117 and in the commentary quote below, suttas such as the Karajakāya Sutta may appear in contradiction.
For example, on a supramundane level, when Angulimala was in the stream to Nibbana (for arahantship), his mind would have been free from 'self-view' therefore free from suffering. However, this mind would have probably experienced the results of past kamma in the form of painful feelings & residual defilements (per SN 36.6).
When we are non-returners practising for arahantship, we might fully understand the Karajakāya Sutta (rather than theorize & speculate, as I have done).
The Awakened One, best of speakers, Spoke two kinds of truths: The
conventional and the ultimate. A third truth does not obtain.
Therein: The speech wherewith the world converses is true, on account
of its being agreed upon by the world. The speech which describes
what is ultimate is also true, characterizing dhammas as they
Therefore, being skilled in common usage, False speech does not arise
in the Teacher, Who is Lord of the World, When he speaks according
Mn. i. 95