the rarity of Crispus VLPP from Trier is one of the factors that makes it difficult to determine if it is official. It is hard to compare it to official issues as there are not many. There are a few things that are unusual, besides the bust and obverse legend that is not listed in RIC VII for Crispus for any issue from any mint. Mainly, the altar is unusual in its border decoration and the shield is plain, they usually have elements at around 11 and 1 o'clock, like wreath ties (I think that the victories are actually holding a wreath instead of a shield, see the Magnentius coin below, which is described as victories holding wreath) Below is an example that clearly shows what I am talking about. It is from Ticinum, but all the VLPP's from London to Siscia have the design.