That quote to me justifies the findings and conclusions you have stated. If we are going to be strict and base our conclusion on evidence from the comparison I would probably state the conclusion as:
The findings demonstrate that lift predicted is somewhat comparable between xflr5 and CFD, with the CFD prediction showing a slightly lower lift value with comparable viscosity settings and xflr5 showing higher, and as described and supported by the quote:
This conclusion is evident in drag also, where the drag present in the CFD simulation is much higher than that predicted by xflr5, without any data on the experimental results, the difference could be a range of things including the above mention of optimistic viscous results, CFD turbulence modelling, mesh refinement (until a mesh independence study proves otherwise) or uncomparable boundary conditions between CFD and xflr5.
I think that is the limit of what we can draw I think your statement on drag accuracy is fair, but we cannot say from the evidence we currently have, in this topic/simulation/review of documentation that CFD is better than xflr, but more a suggestion that it is true, and this would be in my opinion enough to act upon
Awesome project and a great contribution to the forum for future reading.
All the best,