the goverments have plan to create their own cryptocurrenicies, so the btc and eth was just testing currencies to see how it works and get people to use with cryptocurrenies?
No! Governments are only fearing bitcoin and decentalized currencies because people are continuing to adopt it, they already know cryptocurrencies is the future currency. But, governments are only compromising what cryptocurrencies are, cryptocurrencies are supposed to be decentralized, but governments are working hard to centralized it.
first whats wrong with fiat currency? the cash is works good nothing wrong with this
When the governments have already dawning to know fiats are not accurate enough, and that cryptocurrencies can be created in a more transparent way and hard to edit or manipulating ledger unlike fiats.
second how they are going to control how much to issue the currency and how the value will be backed?
Governments are governments, their centralized cryptocurrencies will be controlled like normal fiats which are depreciative assets. So, governments owned cryptocurrencies which will be centralized will be manipulated in price and value like fiats, which means the governments cryptocurrencies will be depreciative assets.
and by who the transparanscy is guranteed?
Government owned cryptocurrencies will be transparent if they use a transparent and impossible to edit ledger, but let us see if such will be the case. But, know that the centralized currencies be it fiats or cryptocurrencies will be a depreciative asset.