Dear Andreas,
ARTEMIS is not suitable for large domains since it does not account for wind growth within its domain. It also requires a much finer mesh than the rest of the Telemac modules. If you wanted to couple ARTEMIS with T2D-SIS, the you would have to run everything on ARTEMIS's mesh which would increase computation times dramatically. Also ARTEMIS does not readily output TPR5 (Peak period R5) that is required by SISYPHE to account for wave action.
As you can see, ARTEMIS is not suitable for sediment transport studies, unless you are proficient with the Telemac system and can do a few adaptations.
So I would advise you to begin with a TOM-T2D-SIS coupled model that is working out of the box. There a plenty of things to master in making a good coastal sediment transport model with TOM-T2D-SIS and reflection is the least of your problems. I would be more concerned with diffraction when coastal structures are involved. As you become more expert with TMS, there are ways you can incorporate ARTEMIS in you study.
Regards,
Costas