When I export my project in captivate scalable in html5, fonts lose sharpness. This has some solution. It seems very strange to me that captivate does not treat the typography as vectorial.
You are talking about a non-responsive project. For those projects the text containers are converted to PNG's on publishing. Reason is that you can use any font, are not restriced to websafe fonts. That is not the case for responsive projects.
You can force to have the fonts rendered on runtime if you turn each text container to dynamic text, which means thaty you need to insert a variable. That can be a user variable with no value.
Another approach which I use sometimes is to create SVG's from text. Those are vector based.
It is a good solution, but could there be any solution related to the code that Captivate exports in html5 ?, I mean, there may be something in the lines of code that can be deleted so that the texts are not converted into an image.
Sorry, cannot help you with tweaking the code. For the reason i mentioned Captivate has always converted to images to preserve the chosen font in case of not being a websafe font.
The conversion of text to images doesn't happen in the output HTML5 code. It happens inside the Captivate application BEFORE the content is published out. So there's nowhere that you can 'delete some code' to get things to work the way you want.
If you want none of the text to be image-based, Lilybiri's suggested methods are the only ones available to you.