It seems that the Fortran interface is mostly meant for writing and not reading. To my understanding, it is not possible to read data from a savepoint with meta-data...
call fs_create_savepoint('sfc_sice-in', ppser_savepoint)
call fs_add_savepoint_metainfo(ppser_savepoint, 'ID', 1)
...will exit with an error saying that Serialbox: ERROR: savepoint 'sfc_sice-in {}' does not exist. While the above is ok for writing (specifying meta-data after creating a savepoint is ok), for reading this does not work.