I don't why,when I tested text and different font styles,text displayed on browser,but when I ask someone to test or play game in html5 export in browser, some text not displaying or not displaying everything.
Could be a device does not have a font installed with the browser or a number of things. But honestly don't know the cause/reason.
It is generally advised you use a sprite font instead of text if possible.
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If you use an uncommon font with the Text object, it won't show the same for anyone who doesn't have the same font installed.
Web Fonts or SpriteFonts don't have this problem and will show the same for everyone.