Setting coupling interface for precice in an imported complex geometry

Hello everyone,
I have imported mesh created in SALOME, with its surfaces defined for boundary conditions.
image

I am coupling my fsi study between fenics and openfoam using Precice.
For precice to understand the coupling interface in the solid solver, the surface 3-int_walls (see image above) needs to be mentioned in
precice.initialize(coupling_boundary, read_function_space=V, write_object=V, fixed_boundary)

I am unable to use SubDomain class, as I can’t use an expression to define coupling interface in a complex geometry.
Please help me correctly input the coupling boundary information from my facet_region.xml file to be fed into the precice.initialize()

Thank you

Please ask at https://precice.discourse.group/ since that is the support channel for precice. Closing.