Q: What is citation score?
As far as we know there is nothing like citation score. There is the CiteScore, which is a metric to help you track journal performance). Basically, it's a metric like impact factor, H-index, SNIP (Source Normalized Impact per Paper), or SJR (SCImago Journal Rank). CiteScore metrics include 8 indicators that monitor the citation impact of a journal by determining the number and percentage of citations and documents in any journal. These reflect on the impact of the journal.
You can find more details about CiteScore here.
The errors you have mentioned seem to be very minor proofread errors. Generally speaking, such errors are not a big deal and can be fixed at the copyediting or page proofing stage. However, if you feel that these might create a poor impression on the editor (since you were expressly asked to do a language edit), you can send a polite email to the editor mentioning that a few minor proofread errors occurred due to oversight and attach the revised manuscript with the corrections.
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