You might have some luck with the right EDS file(s). Consuming a tag is fundamentally similar to typical scanner/adapter type Class 1 communications. The key is how to request the data to read - by tag name, as with a CLX produced tag, or with assembly instances, which is the usual way. The first time I saw this was with Schneider Electric EIP modules - adding the correct EDS files to the config allowed for specifying the tag name and it is then possible to consume the tag from the Logix platform.
Can your Codesys device use EDS files for configuration? My limited Codesys experience with EIP has always been using assembly instances but it may now be possible to specify an EDS file.