Notes on Configuration Examples
The configuration examples on the strongSwan website are actually regression test scenarios. In order to run all of them, pretty much all of the plugins are required and get built and installed. That’s why load statements are used in each scenario to only load those plugins that are actually needed for the test case. Doing this is generally not recommended. Normally you just enable and compile the additional plugins that you need and load them all implicitly without any load list.
The config files in these examples are not meant to be used literally. They just serve, well, as examples. Attempting to understand each setting and its effects is definitely advisable. In particular, time settings are explicitly set lower than usual to make the test runs shorter. Check the man pages or the documentation for the configuration files for details.
Also important is that the scenarios on the strongSwan website are always for the latest stable release (check the strongSwan version stated on the overview page of the test run). So you might find scenarios that use features that are not available with your strongSwan version (or configure them with different settings).