The message is shown in suck stock reports to let users know that the numbers they are seeing are subject to change.
If there is any reposting in progress, it will show this message. If not, it wont.
“Report might show incorrect item valuation.” means it might show outdated valuation rate at the moment. Nothing to worry about.
Since you cancelled backdated transactions or undid them, the effect on the future entries and hence the total valuation is computed via repost, thats it.