Likely he made all of them by himself, based on old photos of trams that were once existed in Surabaya until 1978.
Unlike tram network in Jakarta that was inherited by PPD*1 and operated until 1962, tram network in Surabaya was directly inherited by Indonesian Railways, hence even after its abolishment in 1978 all of the RoW and infrastructures of former tram network (even former stations) are still under the ownership of Indonesian Railways.
*1 : PPD is the abbreviation of Perum Pengangkutan Penumpang Djakarta, a state-owned transport company that still exists today as one of the operator of city buses in Jakarta)
For the one interested, the Frankenberg route can now be found on DLS. There's some sessions as well, but I think those only work in T:ANE unfortunately. The route works in TRS 2019, but the sessions will not be working correctly