Time decay would cause the short put position (in the traditional IRA) to increase in value and would cause the long call position (in the Roth IRA) to lose value, all things being equal. When held in the same account, these two forces offset one another, but in the scenario you are planning, theta (the time decay factor) would operate to move value in the opposite direction you intend.
It is likely that price action (delta) would be a bigger factor, but you'd still need to find a trade where time decay is very slow. I'm talking LEAPS at the maximum duration (almost 3 yrs) held for just one year at a time before rolling the next year up (e.g. from the Dec 2020 expiration to the Dec 2021 expiration when it comes available.).
Of course, the stock market has down years during which time value would flow in the opposite direction, from Roth to Traditional. We could see multiple down years in a row, at which time the value of your Roth could be too depleted to continue playing the game against your traditional IRA. For example, after 3 years of negative stock price movement, if your tIRA is $50k and your Roth is 10k, the strategy might no longer be possible except at a too-small scale to undo the damage in a timely manner.
Last consideration: You would only be able to do this strategy for up to half the value of your combined accounts unless you put yourself at risk for margin calls and/or took out an expensive margin loan. E.g. if your tIRA has $100k in it, and your Roth has $100k, you could only sell puts in your tIRA controlling the value of $100k in shares/units, not the full $200k you have to invest. That way, if you are assigned, you always have 100% of the cash required to buy the shares or exit the position in your tIRA. If your broker allows you to extend beyond 100% cash coverage, say to the 50% cash coverage needed to fully invest both accounts, you are at risk of a margin call if stocks drop by too close to 50% in the opinion of your broker. Stated another way, if each account has cash worth 100 shares of SPY, you could only do the strategy for 100 shares, not the full 200. So you'd find something else to do with the remainder.
This is still an intriguing idea, which probably has a historically high probability of success.
I'm more likely to just buy and annually roll 3y calls with 10% of the money in each of my accounts. That's 100% equity exposure with only 10% downside risk. But time decay works against this strategy.