Hi and welcome to the forum! 
Thanks for reporting this issue. We have lately been dealing with issues related to the initialization of our logging, which relies on log4j.
This specific case seems to be a bug in the Tomcat's implementation for JUL - according to the stack trace you provided, the construction of an org.apache.juli.AsyncFileHandler instance causes the invocation of a static method of LocaleProviderAdapter, even though this happens during the LocaleProviderAdapter class's static initialization, which means a static method is invoked on a non-initialized class.
Nevertheless, it seems that we can avoid a lot of these problems by delaying our logging initialization. This is easier said (or written) than done, as we will need to distinguish logging of events before and after the initialization, so this is something we will have to look into.
Currently, as long as there are no other side effects, please continue using the Java agent and just ignore these errors until we decide how we deal with them. If you DO encounter side effects, please let us know.