Hi Christophe,
You are correct. In this context, nodes refers to each of the entities in the customer organization, including the parent(s).
Unfortunately, this is a known limitation of the organization tree modeling used by Alliance. Please also review the linked topic in Community below:
Organization Tree = too limited | IFS Community
There is a suggestion to export the data via SQL with code supplied in this topic as well as confirmation I had received from R&D this will not be adapted or changed with the limitation to remain at 100.
Besides, honestly, how would you display 2039 objects on the screen in a meaningful way and also not consume memory resources on the client. Imagine, in a situation where you have three levels, you have a parent (1 node) and the second level down are regions (say 8 nodes) but then each region distributes the remaining 2030 nodes as a third level with the display designed to show it horizontally. This does not sound very feasible, etc.