Look:

<link indent="10" ref="intro:1">ааааааа ббббббббббббб вввв</link>
<link indent="10" ref="intro:2">Сильные элементальные духи</link>

In xml 3 word in each link, but the last words are glued together. The problem is only visible when using a Unicode font. With English text all OK.

I'll take a look as soon as I can.

Thanks!
I liked your mod. I would not like to look for another :)

I pasted your xml tags in my demobook, I can't reproduce the issue :/
Do you have the full xml book that shows this happening?

Font size = 1

<book title="Demo / Feature test book" cover="gbook:demo" fontSize="1">
    <include ref="gbook:xml/standard.xml" />
    <chapter>
        <page>
            <link indent="10" ref="intro:1">ааааааа ббббббббббббб вввв</link>
            <link indent="10" ref="intro:2">Сильные элементальные духи</link>
        </page>
    </chapter>
</book>

This is full xml for bug.

I found the issue -- it is nothing to do with cyrillic! When I word-wrap texts, I was removing the space from the beginning of the world, so the next line would look right, but without that space, the measured size was not bigger than the line anymore, so it was placed in the same line, but without the sapce!

I will fix soon.

v2.6.5 has been uploaded to maven, and will be available in curseforge after it's reviewed. It should fix this.