Sometimes the names are allusions:

Rachael - Biblical reference - Rachael was the name of Jesus' grandmother - the name also denotes purity and gentility. Also refers to a story where she was unable to marry her beloved Jacob for seven years (Take your pick - no one can be sure of what Dickens thought, but it will be something like this)

Stephen - Similarly Biblical - was one of the early church leaders - Blackpool - a popular coastal holiday resort at the time ( and now) probably refers to the Fact v Imagination theme.

Sissy (Cecilia) - Biblical - a sainted virgin protected by angels from being ravaged. Jupe... not really sure, but sounds like dupe - to be cruelly tricked (probably to denote that she is an innocent victim of the industrial system)

Gradgrind - denotes hardness and grinding

Bounderby - A bounder is the Victorian term for a rogue

Sparsit - like Bitzer - the combination of harsh letters has an almost onomatopoeic sound - invokes the words - nasty, bitter.

Sleary - makes you want to say 'Sthleary' picking up on his unique speech patterns - denotes perhaps a blurring around the edges, which fits into his role to oppose 'the hard fact fellows' who are all edges, squres and precision

Hope it helps