For concat trees, add a qualifier 'numeric_identifier' and use it in the concatenated alignment. Once the tree is done, use ete to replace the numeric identifier with the OTU meta value.
When a concat object is added to the Project, the OTU meta is backed up as 'original otu meta', and then characters that break raxml or nexml are replaced by _ro_.
For concat trees, add a qualifier 'numeric_identifier' and use it in the concatenated alignment. Once the tree is done, use ete to replace the numeric identifier with the OTU meta value.