This is the "No game no life" I knew.
From now on, please ask your editor to loosen your schedule. (Since I can read Japanese I know you're in the period of sick leave and 育児休暇. Glad you took it.)
Since writing is a creative work, having inhumane schedule weaken your output severely.
And it reflected on the styles of your writing. Very clearly. Vol 1-5, vol6 and vol7-8 were 3 different styles of writing. vol1-5 with ギャグ&下ネタ, and vol 6 without it.
Vol 7-8 were something else.
Even as a foreigner, I saw that the 誤字脱字 and informal or improper usage of Japanese writing were all over the place. It looked like your second or even first draft directly put into publication.
All those ideas, all those touching stories, all those 説得力 could be further polished to make it even a greater piece than vol.6. And it somehow fell short(only a little bit, don't be discouraged!), all because your editor told you to meet the deadline. とても残念です。
I'd like to see the パーフェクトバージョン of NGNL 07.08 in the coming anime adaptation. It will be the second chance of 双六編, like reincarnation.
Vol.9 is a great piece, with all the 伏線 and keywords 回收 near the end of this volume. Very, very touching story even with the mixing of your 趣味&ギャグ&下ネタ with it. This is what it should be when I say "No game no life is a masterpiece".
Last but not least, since you're well-educated and full of curiosity, I guess you've already googled a lot based on your condition, and consulted your physical therapist with those google results. Most of the cervical problems could be solved(or conditions treated) as long as you follow the orders from your doctor.