You will not have to worry about charging at high C. First the battery tender only puts out 1A, second the BMS charging only path resistance is set that charge current is very limited even at full absorb level external charging voltage. When BMS does re-engage the battery tender will limit current to about an amp.
If you left it connected for a week or two, the battery tender might take it up to 14.2v before dropping back to 13.2-13.5v. You should probably avoid letting battery charge sit for days at 14+ volts while tender is trying to make it to 14.2v.
Some battery maintainers do not have the 14.2v absorb cycle. They just sit at 13.2-13.5v.
My suggestion was to use the maintenance charger to raise the battery voltage above the lower knee before subjecting it to a high C rate change.