Robot Army 0.2.1 will be released in about 6 hours which includes a huge amount of cool new stuff plus many bug fixes and particularly a way to repair games which have Robot Army + Factorissimo and have ended up with the entity surface-related error message.
During the 0.2.0 -> 0.2.1 migration, I will be searching all squads and their unit_groups and the members of the unit_group and if the surface values are not the same, the unit_groups will be disbanded and will be later re-created.