It seems that the fixed-in version is a bit weirdly set in those issues - e.g. LPS-14220 is a subtask of a story in LPS-14414, which is stated as completed for 6.2.0. Careful: I did not fully read through all of the issue's descriptions, links and mix what I read with the answer (and comment to) @yannicuLar gave
Basically, this seems to be a new feature. The way to backport it to your installation is to identify the relevant commits (e.g. download the repository from https://github.com/liferay/liferay-portal or https://github.com/liferay/liferay-plugins, identify the relevant commits (they all contain the LPS number), "backport" them (e.g. see if they can just be applied to your codebase or if they need manual adaptation because the whole code changed.
Some features are easier to backport than others, I can't tell about the complexity for this one.
In order to separate your changes from Liferay's core changes, you should try to implement this in plugins (or patched plugins) rather than changing the original code and recompile. Most likely it's only the kaleo-web plugin that's effected, but if there are core changes, you'd be better of having them isolated in plugins.
The simplest (and most futureproof) possibility is to wait a bit for 6.2 (RCs are already out) and upgrade your portal to this version. If you want to stay on a version that gets updates, you should do this soon anyway.