Indonesia has reduced the price not the Korea, If Germany asked for a lower price they will pretty much do the same,remove some cutting edge systems and downgrade to basic variant for others. Don't expect a Ferrari for the price of Lada.
Things happen in trials, thousands or more from most basic switch, anchor deploy and lift time, emergency systems, ballasting time etc are tested. These shouldn't have gone public for sake of showing 'korean subs have flaws'. The flaws not always refer to a part not working but also related to performance of the sub, such as surfacing time, diving time, ballasting time, tilting angle at malfunctions there are dozens more like this, also vibrations and noise measurements.
Point of the trial is to correct possible errors, especially for the first ship of the class the process is more intense and tedious.
Trials are also important for rest of the ships in the class because a true serial production doesn't exists in the sea platforms (complex ones), doesn't matter how many produced the newer hull would be still an individual hull and considered so, thus all trials are done from scratch except the ones related to main characteristics.