The ROCC is intended to be a wide ranging and long term tool. The levels for each domain are laid out across definable progressions that impact on communicative competence, and with a range from emergent to competent across levels 0-5, some may seem like a big jump.
A person may seem to sit between two domains because they are only just showing skills in a particular level, or because they are almost showing skills at the higher level. Using half measures may seem like a solution to separating these but it only creates a need for more descriptors. As we always say, it’s not about the score but the conversation, so if someone sits a bit longer at a particular level, that’s ok.
If you are finding it difficult to decide on a score, give the score that gives you the most certainty, and put information in your comments section to clarify. Maybe you want to say that this is a new skill for them, or define what it is that they still need to learn before moving to the next level. Instead of ROCC definitions for half levels, your comments section is the place to make notes about aspects specific to your person within that domain. If someone is on the cusp between levels, then writing the additional information might give you clues about what areas you might need to focus on to help your person get to the next score.