The reason for it being read-only is that it reflects the IP address of the main connection when an element may have multiple ones.
Via automation, it is possible by resorting to SLNet calls but these are somewhat tricky to implement and error prone.
My suggestion is for you to have a look at element export and import via CSV where you can modify the fields manually and edit elements with it (reference: Importing and exporting elements | DataMiner Docs)
Alternatively, you could leverage the IDP solution and its Reapply feature that would allow you to create CI Types that would behave as templates and allow you to modify once and apply to all (reference: DataMiner IDP app | DataMiner Docs)
The IDP option can also be automated to be run on a schedule with Process Automation or triggered by automation.