some MYANMAR TEXT cannot type properly in InDesign - Pyidaungsu font, Pyidaungsu Number font

I am actually the kind of person to campaign against importing the idea of italics into a language that doesn't already have italics. I don't feel good about trying to tell you about how Myanmar text should be formatted; looking at my very American name, and then looking at your name, I suspect that you probably know far better than me what Myanmar text should look like! However,  I don't necessarily agree that it is a user need; when I see it myself, it's usually a boss need.

As in: here's a story I hear on a regular basis. "My boss told me that he wanted these pullquotes in italics! And this Arabic/Burmese/Chinese/Dari/Ethiopic/Farsi/Greek/etc. font doesn't have italics! What do I do? I need someone to fix this font for me! Or my boss will be mad."

To which I respond: "This language doesn't have italics in its typographical tradition. That's because the word 'italic' means 'in the style of the calligraphy of wealthy and literate Romans, who 2000 years ago lived in the place we now call Italy.' If you need typographic emphasis, you need to figure out what those Arabic/Burmese/Chinese/Dari/Ethiopic/Farsi/Greek/etc. peoples use when they need emphasis. Sometimes this is as simple as using a bolder face, or using an underline. Sometimes it's more complicated."

And then I hear back: "But my boss..."

And I respond "That's what actually needs to be fixed, here... your bosses' expectations." 

Now, this may not be your situation. I would say, if you don't want to make fonts yourself, or pay someone else to make fonts for you, and Pyidaungsu doesn't have the italics you need, then you are going to need to switch fonts. I note that there actually is an oblique face of Myanmar Text. To my eyes, it looks like someone took Myanmar Text and just skewed it to fake an oblique. So it may be just as bad, typographically speaking, as using the skew tool in InDesign! Sorry that I don't have a better answer for you.