also, I agree that the reverse sulfonamides look attractive. A seach of the ChEMBL data reveals 124 antimalarial compounds containing a thienopyrimidine core. Not all have IC 50 data against plasmodium falciparum and therefore its not simple to compare. However, I found some compounds of interest..post coming.
Additionally, I looked into bioisosteres of sulfonamides and found this paper: DOI: 10.1002/cmdc.201200014
Sulfonimidamides as Sulfonamides Bioisosteres: Rational Evaluation
through Synthetic, in Vitro, and in Vivo Studies with g-Secretase Inhibitors
which could validate exploration of some sulfonimidamides.