Paph sanderianum isn't usually considered hard to grow, but can be difficult to get it to flower. The 10C is too cold to be ideal. The average night-time low temperature it gets in the wild is about 20C year round, with near 30C days. Your humidity is acceptable, above 75% is probably better if temperatures are where they should be. Needs good air movement. Sensitive to high fertilizer levels and salt build-up in the media, so fertilize less than many other orchids. Needs somewhat lower light level than most other multi-floral or complex hybrid Paphs.