Just use 2k clear in thin coats it will fix a Matt finish put it on thin at around 24 degres do not try to get a shine on the first coat just aim to cover the base coat thinly. Give it 20 mins At least before applying second coat. Let it merge with the last coat. You can then leave it for a while it will continue to level into the last coat for a while. If it still looks rough leave it over night to dry remember thin coats 1 tin is just enough. 2 tins is to much. Then go again with another final coat.