April had lost what made her April by then. She wasn't a "wave" any more. That's why the Dark People didn't recognize her. They will likely recognize Saga as April.

I did not know she had been stripped of that honour!

In Dreamfall Chapters, book four, when Brian Westhouse was in Abnaxus's abode with Zoe, he was trying to translate the words from a book called the "Annals of Dreaming". Brian Westhouse said to Zoe; "It's a rough translation, the English language isn't up to the task". Was this a slip-up by the writer? I thought they speak alltongue in Arcadia and not English.

Not necessarily. Westhouse and Zoë likely speak English with each other.

But how would they know if they were speaking English to each other or not? If you go back to "Dreamfall" when Zoe spoke to Benrime, Zoe said to her, "How come everyone speaks English here?” And Benrime said, "Eng...lish?” No, Child, we speak Alltongue, as do you." Zoe thought she was still speaking the English language and did not realise it was automatically converted to Alltongue and this also happened with April in "TLJ" - although, unlike Zoe, It took a little longer for April to grasp Alltongue.

Abnaxus' Abode glitch: Instead of a cutscene of Hileriss and his goons walking away (or chasing Crow) I get a blank white screen and then they are still there, making it impossible for Zoe to enter th Abode. I did the prerequisite talking to him and having Crow fly at him to divert their attention. Now what??