Search plugin (1.7.x) doesn't work correctly

Greetings!

I have problems with new versions of Search plugin. Currently I want to migrate from old Openfire server (3.8.2) to new (4.5.1). New server works just fine except search plugin. This is a critical problem that prevents all migration. We have about 600 users here. So, I try to describe in details:

For example, there is a user “Иванов Пётр Сидорович” with login “ivanov-ps”. Russian name, English login.
Old server (OF 3.8.2 + Search 1.5.1) allows me to search this user as “ivan”, “Иванов”, “иванов”, “ИВАН”, “сидор” etc.
New server (OF 4.5.1 + Search 1.7.x) plugin makes difference between uppercase and lowercase letters now and doesn’t give results if there is no 100% match. For example “Ivanov” is found, “iVanOV” is no result. There are no any interesting settings for it in console. Please help to solve this problem or to deliver this information to plugin developer!!

Also search doesn’t work at all in macOS! Both old and new servers and Spark clients 2.5.8 and 2.8.3. Linux clients have problems too. I believe it is connected with letters codes in different OS.

This is a bug report regarding case sensitivity https://github.com/igniterealtime/openfire-search-plugin/issues/10

As for Spark, it is not in active development for a while. And there were no macOS developers ever working on it, so macOS version may have more issues.