CDI does not support arrays or structs in complex data formats (JSON, AVRO, PARQUET). It only supports primitive data structures, basically comma separated data in those formats.
Informatica does have the service to do this natively in CDI-E (elastic). CDI-E can read/write complex datatypes with no code required.
CDI can only do this with calling some sort of code.
What about the following idea? It definitely works in PowerCenter, so it should do in IICS as well, but I can't guarantee it works without any additional tricks I don't know.
Forward the contents of the array "label" to an Expression transformation.
In this EXP, construct one long string out of these (in your case, four) values using a variable port of appropriate length.
Forward the contents of this variable port to an Aggregator transformation, alongside with all "ID" ports of your input.
The AGG will deliver only the last record per "ID" ports (meaning this is the group-by port, resp. the "ID" ports are the group-by ports, depending on whether the "ID" consists of one port or several ports).
Now re-join the output of the AGG with the "original" data stream (without the "label" array), based on the "ID" port(s).
This way you get the cumulated string constructed from all "label" values per "ID" attached to your actual data stream.