Step-by-step Solution:

1. Convert each letter to its position in the English alphabet:
   \( A\to 1,\; C\to 3,\; F\to 6,\; J\to 10. \)
2. Look at the numeric sequence of positions: \[ 1,\;3,\;6,\;10,\;\dots \] Compute the differences: \[ 3-1=2,\quad 6-3=3,\quad 10-6=4. \] The successive increments are \(2,3,4,\dots\) — that is, the increments increase by 1 each time.
3. Therefore the next increments should be \(5\) and \(6\). So the next positions are \[ 10+5=15,\qquad 15+6=21. \]
4. Convert these positions back to letters: \[ 15 \mapsto O,\qquad 21 \mapsto U. \] So the next two terms are \( \boxed{O,\;U} \).
5. (Alternative observation) The positions \(1,3,6,10,15,21,\dots\) are the triangular numbers \(T_1,T_2,T_3,\dots\) with \(T_n=\dfrac{n(n+1)}{2}\). The \(n\)-th term picks the letter at alphabet position \(T_n\).