missing glyphs on web pages I have a rooted Galaxy Note Pro. 

I'm annoyed at black blocks that appear instead of whatever symbol, when reading web pages.  I copied Code2000, Symbola, and the BMP Fallback ttf files to /system/fonts, but (e.g. https://en.m.wikiversity.org/wiki/Reed%E2%80%93Solomon_codes_for_coders#Finite_field_arithmetic ) I still see a block instead of the symbols for Real and Integer domains.  This test page shows lots of blocks in Firefox. The Android browser simply skipps them instead. I also tried Opera.

Is there something needed to register ttf files, other than copying them to the directory? ( Total Commander remounts the file system r/w ) and rebooting?

It's annoying that I can display Tamil, Myanmar-extended-A, and other things I can't actually read, but am missing symbols and marks that appear in pages I do wish to read.
Android keeps track of fallback fonts via a file at /etc/fallback_fonts.xml. After adding your fonts to /system/fonts, you can add a new family node to the XML file like this.

&lt;familyset&gt;
    &lt;family&gt;
        &lt;fileset&gt;
            &lt;file&gt;Custom-Font.ttf&lt;/file&gt;
            &lt;file&gt;Another-Custom-Font.ttf&lt;/file&gt;
        &lt;/fileset&gt;
    &lt;/family&gt;
[rest of file...]


Make sure to make a backup first, and you might need to reboot for it to take effect completely.