Without seeing/knowing the details, hard the say anything for sure. If you use Report menu -> Send test report to developer option, I can examine the situation, verify the possible errors and advise about how to improve the situation.
Likely there is no "false reading" of course. I can confirm that Hard Disk Sentinel properly supports hybrid hard disks (of course) including your hard disk drive (even version 5.50, but yes, would be better to check with the latest version which has highest possible compatibility).
Support -> Frequently Asked Questions -> Why other software displays different health? Which is correct?
which generally describes the situation. I'm afraid it is completely normal and expected that other tools do not report any kind of problems, making their use (at least) questionable. But if other tools show "better" status, it does not mean they are correct - just they are simply not reporting possible errors, reallocations and so.
This is very common for manufacturer-specific tools, as they designed only to minimise warranty replacement and report only if the error-threshold is reached or not. They never report possible issues, degradations - and most other tools work similarly, happily showing "perfect" status for almost failing hard disk drives.
Chkdsk is also not really useful: even if sounds surprising, it does NOT check/report possible problems with the physical hard disk, but checks/fixes the logical drive (partition) only. It can report problems on perfect hard disks - and can never report issues on a failing drive.
The above described numerous times on this forum and on the website...
You did not mention if you used the PROPER ways to test, the hard disk tests offered by Hard Disk Sentnel, described at
Support -> Frequently Asked Questions -> Hard disk health is low or recently changed or I just installed a new (used) hard disk. How can I perform a deep analysis?
as these designed exactly to verify, investigate the situation: reveal / confirm problems OR ensure that the hard disk is now stable or not. It is more sensitive than other solutions in reporting real disk problems, including retries, slower areas and so (which are usually ignored by other tools).
And if the hard disk tests show no errors, complete with perfect results (which means that all possible bad sectors are already reallocated), then it means that the hard disk is now stable, can be used: and in this case, yes, the health can be improved back (even to 100%) in Hard Disk Sentinel of course.
This is also described numerous times, for example at
Support -> Frequently Asked Questions -> How to repair hard disk drive? How to eliminate displayed hard disk problems?
Generally if all bad sectors are already reallocated, then yes, *ideally* the hard disk seems perfectly working, all sectors are readable/writeable, because the spare sectors used instead of the original bad sectors. This is why other test methods/tools can show "perfect" and even the disk tests in Hard Disk Sentinel should show that all sectors are readable/writeable. This is why some (small amount) of bad sectors are even acceptable, as described in the Help and and at https://www.hdsentinel.com/faq.php#health
But it does NOT mean that the hard disk was perfect. It had problems which are already fixed and the status is now stable. However, we can't automatically say "everything is perfect" as this is a bad assumption.
Hard Disk Sentinel designed exactly to reveal and report such issues, to increase attention (and it seems it helped to increase your attention, so did the job).
Ideally after all bad sectors reallocated, the hard disk can be used - but please keep in mind, that sometimes even one single bad sector (which means very high health, eg. 98%, much higher than the health of your hard disk) can cause a broken/degraded RAID array, as just discussed in a different forum topic:
or data corruption/data loss, degraded performance/functionality etc.
So we'd need to KNOW the real status of the hard disk drive, the real amount of problems (and possible degradations, new issues), perform the tests and then improve the health back to be notified about possible new problems/degradations only.
Usually hard disks with so low health suggests that new and new problems will likely happen with later use, so constant monitoring is essential in this case.
Maybe you can contact the deveoper of other tools and ask why they do NOT report these, why they ignore these completely ...
These are general information, applicable for most hard disk drives, especially for hard disks with low health where (even if things seem fine now) we can expect new and new issues.
And if you use Report menu -> Send test report to developer option, I can check and advise specifically in your case.