Regarding your 17 questions and comments,
here first our answers:

1. Line 16, replace "E." in the sixth affiliation by "Ernest"

2. OK

3. Line 426, "universe" -> "Universe"

4. The copyediting changes all look okay

5. Line 405, "FLRW" -> "Friedmann-Lemaître-Robertson-Walker (FLRW)"

6. This looks fine

7. Line 732, ’see' should be ’see Fig. 3’

8. Line 748, remove "that"

9. The funding agencies have been identified correctly

10. In Eq.(A4), replace "h.o.t." by "...", and add in line 918 the
    sentence "Here, the ellipsis refers to higher order terms."

11. These references are okay, to the best of our knowledge

12. The DOI links created in the reference are all OK

13. This looks okay

14. The updated page number '046901' is correct

15. Ref. [15] is published online by Cambridge University Press

16. The publisher city is "Cambridge, United Kingdom"

17. Remove references [58-64]

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Additional changes:

Please add the following ORCIDs:

Axel Brandenburg: https://orcid.org/0000-0002-7304-021X
Ruth Durrer: https://orcid.org/0000-0001-9833-2086
Tina Kahniashvili: https://orcid.org/0000-0003-0217-9852
Sayan Mandal: https://orcid.org/0000-0003-3129-5799
Shinji Mukohyama: https://orcid.org/0000-0002-9934-2785

Line 29, remove "imposed"

Line 175, "induced by" -> "in the presence of"

Line 445, remove "now"

Eq. (35), line 1, first term on rhs, put 'u\cdot\nabla' in parentheses

Eq.(35), line 2, make the sans serif "S" also bold

Eq.(35), line 3, make the script "F" also bold

Eq.(36), make the script "E" also bold, just like in (A.1)

Lines 470 and 478, and twice in Eq.(39), make hat e also bold

Line 514, "problem" -> "magnetic helicity"

Line 516, replace "now" -> "then"

Line 580, replace "u(r)" -> "u(x)", otherwise ok

Line 679, replace "helicity" -> "helicities"

Line 748, replace "Even though" -> "Although"

Line 818, remove "right"

Line 824, between "way" and "until", add "from the time when the inequality in Eq. (32) is satisfied".