ICloud – How to restore individual app data from iCloud while keeping all the other apps installed and new data created since the last iCloud backup

I just discovered that one of my apps X "disappeared" for whatever reason from my iPad. It contained MBs of valuable data, and luckily I have an iCloud backup dated a week ago or so which have it all. However, I installed two dozens of new apps since then and likely created some amount of user data that I'd like to keep.

How do I restore that single app with all its data from iCloud while preserving all the other apps and their data installed since the date of iCloud backup?

I've read the related question, but it doesn't directly help in my situation:

1. I disabled backup to iCloud to prevent overwriting the X data in iCloud with an "empty" copy of X. Will simply "disable backing up to iCloud" for X and than backing up all the rest to iCloud (followed by reset and restore from iCloud) solve my entire problem? If so, how to run it properly?

   • when I try to enable backup to iCloud, it needs an Internet connection–which creates a risk that X will be overwritten before I deselect it

   • when I try to disable backing up of X, iOS says that all of my data for X in iCloud will be deleted:

     Do you want to turn off X backups and delete the backup data from iCloud?

2. I've already re-installed the X hoping it will bring all of my user data–but of course it's didn't. Now the question is whether it's better to keep it — to avoid risk of losing its data in iCloud,

   Do not delete the app if its data are in the iCloud.
   Deleting the app, will also delete the app data and its preferences

   –or to remove it, to merge the iCloud data of X with latest data of all other apps from iTunes backup that I create today, right before restoring from iCloud, per this:

   Now restore your iPhone to the latest backup you just made which is as
   per Step 3. This will not erase or replace the apps you installed and restored via iCloud. It will only merge.

3. Alternatively, is it possible to manually "merge" backup of X from iCloud into/with current-moment iTunes backup per SafeHarbor knowledge from this answer?

4. Any other how-tos will be greatly appreciated.

Update: After restoring from iCloud, the X app is not restored; App Store shows an icon to download it from the cloud (which will not restore its data, as I've seen before the reset). Any suggestions?