Your account is much newer, so not as many as others will have, but it's a good example.
There's two patterns:
KEEP / ABSORB: this means that the user has studied both the primary and the alternate term. In this case KEEP is the primary, and ABSORB is the alternate that will disappear, and the relevant mastery/study data will be added to the main term.
MOVE: this means that the user has not studied the main term, only one or more alternate forms. The data from all these alternate terms will be merged and saved as the primary term.
You can see that there are two general categories that cover most of the changes. One is presence/absence of kanji (usually 御) - this is most of them. The second is a much smaller group that shows a switch between number based terms. This one is trickier, and may be a target for people who want to keep both of them (even if the renshuu lists are switching over).
While the base dictionary that renshuu uses places the numerical forms (10月) over the kanji forms (十月) in terms of priority, I can understand a strong case made for wanting the kanji forms to appear in the quizzes. This is open to debate, but ultimately, I need to choose one or the other, and align all of renshuu's materials to that. I did do a test move (not in anyone's data or lessons, just in the way it is presented in the dictionary) for all of the hours (you can see one at the bottom), and I feel that would be ideal for the most number of people - keeping the kanji form. (Note: this is not a setting where users could use which one they want to use in the lessons.)
KEEP: お祖父さん, ABSORB: 御祖父さん
KEEP: お金, ABSORB: 御金
KEEP: ご飯, ABSORB: 御飯
KEEP: 九時, ABSORB: 9時
KEEP: 出かける, ABSORB: 出掛ける
KEEP: 勤める, ABSORB: 務める
KEEP: 子供, ABSORB: 子ども
KEEP: 川, ABSORB: 河
KEEP: 成る, ABSORB: 為る
KEEP: 昼ご飯, ABSORB: 昼御飯
KEEP: 有る, ABSORB: 在る
KEEP: 此の, ABSORB: 斯の
MOVE: お腹がすく TO : お腹が空く
MOVE: ご免 TO : 御免
MOVE: タバコ TO : 煙草
MOVE: 一日 TO : 1日
MOVE: 七月 TO : 7月
MOVE: 九日 TO : 9日
MOVE: 二十日 TO : 20日
MOVE: 二十歳 TO : 20歳
MOVE: 二日 TO : 2日
MOVE: 五日 TO : 5日
MOVE: 八日 TO : 8日
MOVE: 十二月 TO : 12月
MOVE: 十日 TO : 10日
MOVE: 四月 TO : 4月
MOVE: 御代わり TO : お代わり
MOVE: 御兄さん TO : お兄さん
MOVE: 御好み焼 TO : お好み焼き
MOVE: 御姉さん TO : お姉さん
MOVE: 御父さん TO : お父さん
MOVE: 御茶 TO : お茶
MOVE: 御風呂 TO : お風呂
MOVE: 朝御飯 TO : 朝ご飯, ABSORB: 朝ごはん
MOVE: 此から TO : 此れから
MOVE: 段段 TO : 段々
MOVE: 米突 TO : 米
MOVE: 詰まらない TO : 詰らない
MOVE: 0 TO : 〇
MOVE: 10時 TO : 十時