As a Japanese Tax Resident, do I need to keep track of the buying and selling of every investment in an IRA?

As of this year, I am now required to report my worldwide income to Japan.

I use a non-Japanese brokerage.

I understand that with a non-retirement account, when I buy and sell investments I need to keep track of the exchange rate when I buy and sell an investment, as well as the gain itself in order to know what my tax will be.

However, how does this work for an IRA?

I have many years before I will retire, but below are some questions I have about owing IRA accounts while living and retiring in Japan.

1. Do I need to keep track of every transaction within the IRA, calculating the exchange rate of each day a transaction happens?

2. Or, do I only keep track of the exchange rate of the contribution day and then the distribution date (as well as the distribution gain itself)? As in, even if I bought and sold investments 20 times, do I just calculate my contribution and distribution dates?

3. What about investments in the IRA made before I became a full Japanese tax resident?

4. Is there anything in particular I should be aware of?

5. Are IRA distributions taxed at the same 20%ish rate as normal capital gains?

6. Is investing in IRAs still a good thing or do they cause more issues than solutions while living in Japan? I understand Japan doesn’t view them the same as the US.