Do I need to worry when a regular expression topic name can't be validated?

There's no need to take action, provided that you have ensured that the regular expression is correct and matches the topic names that you want to replicate.

AMPS sets up the replication as requested. This warning does not indicate a problem with the configuration or that AMPS has encountered a problem. The warning is to let you know that AMPS is skipping some of the validation that it would otherwise perform, and that you may need to ensure that the regular expressions cover the topics that you want to log and replicate.

Details

During configuration validation, AMPS may produce messages such as:

Warning: Topic '.*' of type 'json' on line 45 has a regular expression topic name that can't be validated against the regular expression topics included in the transaction log on line 456.

This is a warning that AMPS configuration validation issues when a replication destination uses a regular expression to describe the topics to replicate and the transaction log also uses a regular expression for topics to be logged. When both replication and the transaction log use regular expressions, AMPS does not attempt to verify that the replicated topics are captured in the transaction log. Instead, AMPS issues a warning to the console saying that it is not doing that validation.

If you're confident that the regular expressions cover the topics that you need to have replicated, then you can safely ignore this warning.