Why are there rising/falling tones in English-language chanting?

I gather from reading around that the rising/falling pitches that appear in Pali chanting by Thais is due to the tones in the Thai language . But when I see English-language chanting by monks from a Thai tradition, they still have rising/falling tones. See excerpt from the Abhayagiri Chanting Book , with the tones marked: It doesn't seem to match the equivalent Pali. Is there a system that they're using, such as shoehorning the Thai tone rules into English syllables? Or are they just making it up entirely?