Sorry for let you wait.
One of the problems, to find in Level 6, is in the lower left corner:
In the sandy room (from the start of the level up, right, right, up) you can go up or left. If you go left, you have to defeat same Goriya and Keese to get a key. But if you go up, you are in big troubles. Behind you shuts the 1-way-shutter and there is no bombable wall or a walktrough in this and in the further rooms. If you have no key, you have to reset/save.
And almost worse than this 1-way-shutter problem: If you try it again, of course with the key from the left room, you will find in the locked room a stair who brings you to a room one room up from the start screen.
I think that a change from 1-way-shutter to a normal shutter would be the best and minimal invasive intervention.
In the example above it wouldn't not help if it is so.
In Level 9 (4th quest) I'm almost sure, that there could be some bomb dropping enemies. But what does bombs help, if you have no key? There is a stair, in the room below is a 1-way-shutter and in the next room you need a key. Even a million bombs doesn't help if you have no key. Without bombs you have the problem a little bit earlier.
But I love the 4th and Level 9 anyway. A sword, two bombs and one fucking key are enough to get the magic key. I bought 4 keys, because I haven't found the right way. Now i know, that the magic key is "very easy" to find (because NOW I know the way).
Now I'm playing the 5th quest. Quest 3rd.qst and 4th.qst I have played through. My self-made cards of each level are (hopefully) complete. My problem is now: If you ask me something, for example Are there any enemies wthat drop bombs in the area where Link can be locked? and I don't know the answer, I must run Zelda Classic, go to the level and have to look, because I haven't a cheat code or the password for the file. And I don't think that you'll give it to me.