Specific App install from Google Play fails, where to see log?
To answer myself:


Downloaded the .apk of the app on a PC with the help of the APK Downloader tool, and put it onto the phones SD card.
Used Terminal application (part of CM10) to switch to root (su),
then tried to install the downloaded .apk file via pm install com.name.apk


Got an error code: INSTALL_FAILED_UID_CHANGED, googled that and found a solution:


Removed /data/data/com.name.apk/ folder completely via terminal
Tried pm install com.name.apk again -> SUCCESS (Would probably also have worked with normal Play Store install.)


Seems that each app gets a unique UID on first install to manage its access rights on files and folders. If the system thinks it's the first install, it assigns a new one, then can't overwrite/delete old settings/data folders previously set with another UID.