I wouldn't go coining a term.Is there such a term as "syllabic fingerspelling".......can we "coin" it as it relates here?
As far as improving receptive fingerspelling by interpreting letters as phonemes (sounds), you would need a lot of practice to receive words as phonemes such as "D–E–E–P T–R–E–A–S–U–R–E" to "d ee p t r e zh ur".