Calculate LifePo4 charging amps
Not that simple. For "optimal results" each battery should be charged sort-of individually, aka with "balanced charger". You can't just sum up the charging current for the 2P connection, because each battery have different internal resistance, and will charge (and discharge) to a different SOC (State Of Charge). As result, the batteries won't be charged "optimally" at least, and at most will self-drain faster. 

Regarding the current, it looks that you can charge the cells at any current up to 132 A (2C), just the number of work cycles will likely do down with 2C charging. Their "22 A" number is likely the optimal value.

Similar considerations apply to 4S (serial) connection: time to reach the terminal voltage (aka "limited voltage") will be likely different for each cell. The charger must balance this difference.

In sum, just "summing" charging currents doesn't work well, and definitely can't be called as "optimal".