yes,

after your steps, now please to do refinement for the lattice parameters one by one of the cif file also atomic positions.

Your intensities seem to be a little off. What is your background doing? Do you have the correct LP factor?

Also, if all that you're worried about is fitting the profiles, consider doing a Pawley refinement, where the peak intensities are refinable parameters.

Hi,

please check for absorption, depending on the exp wavelength it can be relevant; have a look also to atomic displacement parameters

You say: "I am trying to do the instrument broadening..." What do you mean by that? Are you trying to determine instrumental resolution function by using Cr2O3 with large crystallites and without defects?

If your sample is rather coarse grained, it may be that there is a small preferred orientation effect. In this case, you may do Le Bail refinement (enforce "Arbitrary texture" option in MAUD), which would seriously improve the refinement quality.

Preferred orientation may be one possibility for intensity ratio mismatch and for coarse grain samples this kind of effect become more prominent at synchrotron sources due to smaller beam sizes at sample compared to lab source. The peak profile function and their parameter value also depends on the beamline design and experimental/measurement geometry.

You have done measurements at synchrotron source, the beamline operational peoples of that synchrotron are the best choice which can quickly help you about the instrument broadening parameters and refinement strategy for nano-sized sample.