This isn't really standard English orthography, I'd just remove those asterisks.

If Tatoeba doesn't allow suprasegmentals written then the sentence has to be removed. Editing it would domino effect the existing translations.

I believe that @gleki is trying to convey a stress accent to emphasize one particular word in speaking, but this sort of information may not translate automatically into an equivalent stress pattern in another language anyway.

Besides, in principle, a speaker could emphasize just about any word in the sentence, admittedly with different perceived meaning:

Stressing "I' may imply that others did the majority of the mopping.
Stressing "mopped" —> the rest of the floor was vacuumed or swept.
Stressing "only" —> self-deprecation as to the task's magnitude.
Stressing "floor" (silly) —> perhaps walls and windows were also mopped.

I agree with @megamanenm. Allowing suprasegmentals would clearly be anarchic and would create chaos at Tatoeba with no compensating benefit. As @CK has pointed out to me in the past, occasional ambiguity is inevitable at Tatoeba, and we live with it.

The sentence, however, need not be removed. The sentence is perfectly understandable in at least one ordinary way without the superfluous asterisks. If someone else happens to read with a different intonation than you intended, but the sentence still has meaning, that is still fine.

You can, if you wish, submit an audio recording that encapsulates your intention. But I would just remove the italics and leave the sentence.

This usage is frequently seen online even if it hasn't made its way to printed publications yet. Should we ignore anything that's not recognised officially?

Ok then I will simply remove the translation because it will become incorrect

Well, instead of deleting it, @Gleki, if you feel that without the asterisks it does not adequately translate the linked Lojban sentence, you can simply unlink the two and then release the English sentence for someone else to adopt. Even without asterisks, it is a perfectly correct English sentence which can be spoken in a few different ways — again, not an issue at Tatoeba. Unlike with Lojban, a little ambiguity is no problem in most natural languages.