Currently Corda-IBC implements a ICS-2 light client for HLF using the external process called "fabric-ibc-lightclientd".
Fabric-ibc-lightclientd is written in Go and is easy to implement as it can depend on yui-fabric-ibc, ibc-go and cosmos-sdk.
However this brings unfavorable complexity to development and deployment of Corda-IBC.
In the future, we should replace fabric-ibc-lightclientd with native implementation of a HLF light client written in Kotlin.
For those unfamiliar with IBC, ICS-2 is defined in the following.
https://github.com/cosmos/ibc/blob/master/spec/core/ics-002-client-semantics/README.md