This post concerns a possible method to avoid hyphenation in the word thing ("th-ing").
I did a brief study on the format of the dictionary and while I'm not really clear in my mind about it, I can say that the numbers tell the software whether a given word location is a good place to put a hyphen (if needed) or a bad place to put a hyphen. Basically odd numbers favor hyphens (higher numbers are more favorable) and even numbers discourage hyphens (high numbers are more dis-favorable). Using this idea and the information
here, I tested adding these 2 lines to the dictionary file provided by JSWolf (the English one):
t8h8i8n8g8
t8h8i8n8g8s8
I put those 2 lines near the top, above the first pattern (ie above the .a2 line). I believe this is basically tells the hyphenation engine to not hyphenation "thing" and "things".
I found a place in a book where "thing" was hyphenated as "th-ing" using a dictionary without those lines and was not hyphenated using a dictionary with those lines (no other changes between the two dictionaries). But it is not rigorously tested.
Also, thing is a challenging pattern of letters because "cloth-ing" is a valid hyphenation place but "th-ing" is not.
YMMV, but other in this thread reported seeing "th-ing" so I wanted to report my tests. Good luck!
If it's not clear, you have to unpack the dictionary so you can see the usr\local\kobo\hyphenDicts folder, edit the dictionary with a text editor and then repackage it to KoboRoot.tgz and drop it into the hidden .kobo folder on your device.