I have followed the debates about the nature of the ‘dark sector’ for many years now, and have looked at the mathematical formalisms of all the various candidate models and ideas, some of them in detail. So I’m drawing from a diverse range of sources, not just a single paper or author.
If you look at the bigger picture, you’ll find that many of the alternative models may be better at explaining specific phenomena - but at the cost of failing miserably with other observational data. Furthermore, very many of these alternatives require extra fields or extra dimensions, or make ad-hoc assumptions that aren’t based on any known physics - so they try to explain one unknown by proposing other unknowns, which is kind of useless. For example, the paper you quote assumes the existence of sterile neutrinos below a certain critical mass limit in order to match observations. Other known problems with MOND are never addressed at all.
On a meta level, taking into account all available observational data at this point in time, standard GR still provides the best fit. Im aware of the problems in standard cosmology of course, but I don’t think any of the currently existing alternatives provides a good enough solution. That includes MOND and its relativistic generalisations.