Hello Mikael,
Quite some time ago Pawel Burchard and I discussed also about the Do215, mostly because I have composed several databases of all types of nightfighter aircraft that have been on Venlo airfield in WW-2 with the I./NJG 1.
According to my Do215 database, the number of 105 produced Do215's is almost certainly correct, because for instance the Flugbereitschaft Luftwaffe Kommando Süd-Ost lost a Do215 north of Saloniki and it crashed 17th May 1943. This Do215 had Werkenummer 102, therefore it is likely that the production went beyond Werkenummer 101.
Most of the reference works I consulted do also mention a production number of 105 Do215's.
Hoping to have clearified this subject, all the best,
Marcel Hogenhuis
www.fliegerhorst-venlo.net