Expectations for Sep-23 Quarter, page-15

Personally i wouldn't be taking advice from a online forum if you should top up or not. Go speak to a financial advisor.

TER currently has a great dividend yield. if you are chasing dividends, sure go for it.
TER capital gains* probably wont happen unless management actually do something beyond the current status quo or, outside their influence, the coal price sky rockets. *significant capital gains.

If your super fund is in retirement phase, yes you don't pay tax on the dividends (or other income). The bonus is you get 100% of the franking credits as a refund.
Therefore with your holding on a 3 cent dividend, you would receive $1,800 of cash from TER and $771.43 from the ATO when you lodge the fund's ITR (assuming nothing else in the fund). So total cash in flow of $2,571.43 for each 3 cent dividend.