HART is a dead end. HART must be implenmented in the field instrument and as far as I can see, it isn't. There's no feasible path to faking HART (who's going to write the DD (device descriptor) file needed by any HART master?) If the manufacturer doesn't see that as profitable, how can you afford to do it?
You should investigate what kind of data and abilities the optional OPC server offers.
A modern DCS is always an OPC client which can communicate with an OPC server, which needs a low level driver to talk to the field device. This analyzer offers an OPC server of some sort.
OPC always provides process variables.
OPC sometimes provides diagnostic data.
OPC rarely provides configuration access. Nothing prevents it from doing so, but it just isn't common.
What is available depends on what the instrument provider makes available via its digital protocol, which gets read by OPC.
So you need to research what's available via OPC vs whatever it is that your customer is asking for.