I've decided to write a short guide on how I've made PRS T1 show book titles, TOC, bookmarks, pages in browser correctly in Georgian Unicode. I think this info might be useful to others as well. So here we go:
The outline of the process is as follows: PRS T1 fonts partition is CRAMFS this means that it's read only one can not just copy and paste font files in fonts directory even in rooted system (of course if you're not root you don't even see systems partition). That's why we need to extract fonts CRAMFS image to the reader partition that's accessible from a PC (I've done it on Windows 7 machine) then copy extracted CRAMFS image to PC (you need to have cygwin installed on PC) unpack the image with cramfsck command change the font repack back with mkcramfs command and write back to PRS T1 flash the modifed fonts image.
1. Run Terminal emullator on PRS T1 type
and $ promt will change to # now you have superuser priviledge and can use the following command
dd if=/dev/block/mmcblk2p5 of=/mnt/sdcard/mmcblk2p5.img
to extract fonts CRAMFS to READER partition of PRS T1
2. Move mmcblk2p5.img to root of C:\ directory on your PC, from Start/Run run CMD cd to cygwin/bin directory and type
cramfsck -x d:\ /cygdrive/c/mmcblk2p5.img
I assume your second windows partiotion is d: if not change to whatever yours is. On D:\ you will see 44 font files extracted.
3. Now you need to identify font file which you want to replace. Droid sans is responsible for the book titles, TOC and stuff. I've chosen to replace Droid Sand Thai with Georgian font. I've got Droid Sans Georgian ttf from Android SDK on my PC C:\Program Files (x86)\Android\android-sdk\platforms\android-15\data\fonts this is the path on my system. It comes with Andorid 4.0, there are other fonts as well like Armenian for example.
Idea is that you have to rename not only file name to the font you want to use, to the file name of font you decided to replace, but also font name. I've done this with Font Creator v6.5 you can use any other tool of your liking. This step is important!!!
if you make mistake here you'll brick you device! Don't mistype font name. Once you've done this step make mmcblk2p5 folder on your d:\ drive and put all 44 fonts including modified one to that folder.
4. From CMD promt run this command
mkcramfs d:\mmcblk2p5 mmcblk2p5.img
make sure your CMD promt is in correct directory it has to be cygwin/bin. Now you have modified CRAMFS fonts partition ready to be written to PRS T1 flash. The new file must be smaller in size than original!
5. Copy your new mmcblk2p5.img to sdcard on PRS T1 (it's READER partition, which is mounted when you connect to PC in data transfer mode)
Open Terminal emulator on your read and write the following command
dd if=/mnt/sdcard/mmcblk2p5.img of=/dev/block/mmcblk2p5 bs=1024
of course make sure you have su # promt. You can do this command in recovery mode and then the code will be different. I've done with this code in normal mode.
Wait for a minute and terminal will signal you how much data it written, now you can restart you're reader. AND no more ugly ????????? in squres!!
Disclaimer! This low level operation on system files, potentially you can render your device nonoperational. Do above instruction on your own risk! I'm not responsible for damage you could make to your device.
Credits go to Porukan/Boroda, snarkophilus and j0534ng31 they have made this. I'm a compete noob