Interreg projects with a Bulgarian participant, from keep.eu.
Interreg runs on Jems while the Bulgarian operational programmes run on ИСУН 2020. The ИСУН register therefore contains zero Interreg projects. That is a system boundary, not a filter: no amount of re-querying ИСУН would find them.
For ИСУН we show contracted value; here, the published budget of the Bulgarian partner. Different quantities, so there is no combined total anywhere.
Because Interreg is cross-border by definition, its money lands almost entirely on border municipalities — the ones an ИСУН-only ranking understates.