Sea level rise is certainly significant. But your title implies that it is caused by axis tilt. That’s incorrect. It is caused by groundwater pumping, which is also causing axis tilt. In other words, if axis tilt were magically reversed it wouldn’t make any difference on sea level.
Axis tilt is an effect, not a cause. You should read the original article, it’s less confusing than the summary you linked.
Exactly.
In fact the purpose of the paper is to examine the effect of groundwater pumping on sea level. There are two competing hypotheses: (1) pumping decreases sea level by sequestering water, and (2) pumping increases sea level for complex reasons.
The authors noted that these hypotheses would imply different small changes in axis tilt. They measured axis tilt and found it supports hypothesis 2. The small change in axis tilt is simply a clever way to answer the question, it has no other impact on our life.