YES

# Compositional parallel critical pair system (Shintani and Hirokawa 2022).

Consider the left-linear TRS R:

  b(b(x)) -> c(a(x))
  c(a(x)) -> b(a(x))
  c(a(x)) -> b(a(x))
  b(a(x)) -> b(c(x))
  a(b(x)) -> b(c(x))
  c(b(x)) -> b(c(x))
  a(a(x)) -> a(b(x))
  c(c(x)) -> b(a(x))

Let C be the following subset of R:

  c(a(x)) -> b(a(x))
  b(a(x)) -> b(c(x))
  a(b(x)) -> b(c(x))
  c(b(x)) -> b(c(x))
  c(c(x)) -> b(a(x))

The parallel critical pair system PCPS(R,C) is:

  (empty)

All pairs in PCP(R) are joinable and PCPS(R,C)/R is terminating.
Therefore, the confluence of R follows from that of C.

# Compositional parallel critical pair system (Shintani and Hirokawa 2022).

Consider the left-linear TRS R:

  c(a(x)) -> b(a(x))
  b(a(x)) -> b(c(x))
  a(b(x)) -> b(c(x))
  c(b(x)) -> b(c(x))
  c(c(x)) -> b(a(x))

Let C be the following subset of R:

  (empty)

The parallel critical pair system PCPS(R,C) is:

  c(a(b(x1_1))) -> c(b(c(x1_1)))
  c(a(b(x1_1))) -> b(a(b(x1_1)))
  b(a(b(x1_1))) -> b(b(c(x1_1)))
  b(a(b(x1_1))) -> b(c(b(x1_1)))
  a(b(a(x1_1))) -> a(b(c(x1_1)))
  a(b(a(x1_1))) -> b(c(a(x1_1)))
  c(b(a(x1_1))) -> c(b(c(x1_1)))
  c(b(a(x1_1))) -> b(c(a(x1_1)))
  c(c(a(x1_1))) -> c(b(a(x1_1)))
  c(c(a(x1_1))) -> b(a(a(x1_1)))
  c(c(b(x1_1))) -> c(b(c(x1_1)))
  c(c(b(x1_1))) -> b(a(b(x1_1)))
  c(c(c(x1_1))) -> c(b(a(x1_1)))
  c(c(c(x1_1))) -> b(a(c(x1_1)))

All pairs in PCP(R) are joinable and PCPS(R,C)/R is terminating.
Therefore, the confluence of R follows from that of C.

# emptiness

The empty TRS is confluent.