In German Nyanatiloka uses the even stronger übler Weg, “evil way”.
But it seems to me that the renderings of venerable Sujāto (“prejudice”), of venerable Brahmali (“bias”) and of the Thais (ความลำเอียง) are contextually much better supported.
In particular, consider the treatment of the four agatis in the Mahāsaṅgāma chapter of the Vinaya’s Parivāra:
How is one biased by favoritism?
It may be that someone thinks, “This is my preceptor, teacher, student, pupil, co-student, co-pupil, friend, companion, or relative.” To be compassionate toward and protect this person, he proclaims what is contrary to the Teaching as being in accordance with it and what is in accordance with the Teaching as contrary to it. He proclaims what is contrary to the Monastic Law as being in accordance with it, and what is in accordance with the Monastic Law as contrary to it. He proclaims what hasn’t been spoken by the Buddha as spoken by him, and what has been spoken by the Buddha as not spoken by him. He proclaims what was not practiced by the Buddha as practiced by him, and what was practiced by the Buddha as not practiced by him. He proclaims what was not laid down by the Buddha as laid down by him, and what was laid down by the Buddha as not laid down by him. He proclaims a non-offense as an offense, and an offense as a non-offense. He proclaims a light offense as heavy, and a heavy offense as light. He proclaims a curable offense as incurable, and an incurable offense as curable. He proclaims a grave offense as minor, and a minor offense as grave.
If he is biased by favoritism by way of these eighteen grounds, then his behavior is unbeneficial and a cause of unhappiness for humanity; it is harmful, detrimental, and a cause of suffering for gods and humans. If he is biased by favoritism by way of these eighteen grounds, then he is damaged and impaired, blamed and criticized by sensible people, and makes much demerit.
How is one biased by ill will?
It may be that someone thinks, “They’ve harmed me,” and he feels resentful. Or he thinks, “They’re harming me,” and he feels resentful. Or he thinks, “They’ll harm me,” and he feels resentful. Or he thinks, “They’ve harmed someone who’s dear to me” … “They’re harming someone who’s dear to me” … “They’ll harm someone who’s dear to me” … “They’ve benefited someone I dislike” … “They’re benefiting someone I dislike” … “They’ll benefit someone I dislike,” and he feels resentful. Because of these nine grounds for resentment, he is resentful, hostile, angry, and overcome by anger, and then proclaims what is contrary to the Teaching as being in accordance with it and what is in accordance with the Teaching as contrary to it… etc
How is one biased by confusion?
Biased by favoritism, ill will, or confusion, or by a grasped view, he is confused, deluded, and overcome by confusion, and then proclaims what is contrary to the Teaching as being in accordance with it and what is in accordance with the Teaching as contrary to it… etc.
How is one biased by fear?
It may be that someone thinks, “This one relies on the uneven, on thick covers, and on powerful individuals; he’s cruel and harsh, and might be a threat to life or the monastic life.” Fearful or frightened of him, he proclaims what is contrary to the Teaching as being in accordance with it and what is in accordance with the Teaching as contrary to it… etc.