C:\Users\UserName\AppData\Local\Koinonein BitTorrent Client x64 will be created by the installer and the installer will create the ISO-639-1 folder and content and the geolite2-country.mmdb file will be added also, if you happen to delete
C:\Users\UserName\AppData\Local\Koinonein BitTorrent Client x64 then koinonein.exe will create it again next launch as it needs it’s base folder to store the databases in, this is kind of the behavior you expect for an installed application but not desirable for a portable version so portable will have to be a separate build rather than a combined build.
C:\Users\UserName\AppData\Local\Koinonein BitTorrent Client x86 can only be created by the 32bit version or the 32bit installer but I noticed in a few version back the 32bit was missing from the description in a lot of sites Koinonein is listed on.
Garbage collection was mistakenly left off in 0.1.2.4, it was turned off to make sure memory was being correctly released after torrents were stopped, fixed for 0.1.2.5, but there is also an issue in Libtorrent with peer_class objects that’s been resolved and will appear in 0.1.2.5.
Adding a dark/light theme option is not a problem, feature will appear in a build or so.