QE would need to be taken away very gradually.
Even with QE Japan has experienced deflation
QE in Japan doesn't work because price level has gone to unrealistic level. Property and security price are governed by yield and return of investment, if they go up to unsustainable level, the cost will of course need to go down. Printing a lot of money will only make smart money leave the country to seek better yield and reasonable ROI business.
Japans a bit weird in that their debt is larger than their GDP by a significant amount but people trust that their money will not be lost or stolen in the system or the currency will collapse.
Benefits of having your own citizens holding the debt still to get ROI would be a significant challenge for them and they can't really print money to increase their debt so its a bit of a conundrum.
Debt larger than GDP is fine. A more meaningful measurement would be the country income vs debt level. So long as the country has good income via export and service, the debt can be expected to be paid back.
Countries that have a large enough economy so that their currency is used widely outside of that country's commerce are almost "exempt" from these kind of ratios/statistics
To have someone lend you money, you need to demonstrate the ability of paying back. Income/debt ratio is a good way gauging the person ability to payback the loan. No country can be exempted from this rule unless the debt is dominated in the debtor nation currency.
Countries are measured by their ability to repay by a number of statistics. Some countries have large "stocks" of assets (gold, diamonds, oil, and similar) that they export, the revenue from this could be used to measure a countries ability to repay debt. Other countries have a large trade surplus and as a result there is a lot of foreign capital going into the country. Some countries have very large economies and a country's ability to tax is what is measured as to how it could repay their debts.
When large countries like Japan want to issue debt then can issue it in their home currency as there is sufficient demand for that currency throughout the world.