Doesn't make any sense to extend 15053/4 CPR-LJN Express to Thawe. Thawe already has a semi dedicated train in the form of Chhapra Kacheri - GTNR Express and extending it via a longer route doesn't make sense.
As for ASN-GKP Express, the reason it doesn't get patronage is because it terminates at ASN only and not HWH. Extending it to Barhni probably won't help much. If anything, the extension at the Asansol end is more important and then a "Barhni-Howrah Weekly Express" can capture pax.