Style, you need to ask the author unless it’s prosilver which we support.
Modifications, who knows? As there are none in phpBB 3.2 only you can answer that.
Basically, if you’re editing core code the responsibility for maintaining it is yours through upgrades/updates but, as mentioned, editing core code is no longer recommended
"The more connected we get the more alone we become" - Kyle Broflovski
There are no ‘threads’ in phpBB, they are topics.