> huh I've never used Github
You don't have to use github, there's just a form you need to fill to log a bug report.
Oh my goodness, I solved it.
It all began with me making the demo as essential as possible.
By removing objects, all remained was the textbox, the custom font and the text.
I wanted to keep things as simple as possible, so I renamed the font name just "customfont", and surprisly it works perfectly.
I tried on the original project, and now it's working as intended, with and without manual wrap in the sentence.
What can I say... Wow.
Apparently Construct on Firefox doesn't like underscores and extra dots in font names (the original name was VCR_OSD_MONO_1.00.1.ttf).
I guess case closed?
Thank you so much for your help, really.
Actually, if it wasn't for you suggesting me to send the project as debug, reading the rules, modify the project to make it as essential as possible, by leaving only the interested objects, I would have never found the issue.