I'm an artist and can answer the question about acrylic paint. Acrylic paint is a very common medium for artists to use. It can be used for posters, paintings, just about anything. It's a very thick paint that doesn't drip, but it can smear on your hands if you're generous in squeezing it from the tube.
Labels do often come off acrylic paints, if it's a glued label, particularly if it's got a single glued seam, so the lack of label doesn't bother me. In fact, nothing about the claims that Rebecca painted that message seem implausible to me. That doesn't mean that she did do it, just that it's not far fetched to imagine.
I am 5'3" tall and would have no problem painting a message on the same part of the door that Rebecca allegedly did. Again, did she do it? I don't know, but it's not out of the realm of likelihood.
Most artists, when painting signs or words, tend to use block letters, so the block letters aren't an issue either.
I guess the entire problem with this case, in my eyes, is the child's death. If only I could wrap my mind around what truly happened to him, I think everything else would fall into place. But since I can't accept the beginning of the story, I can't get to the ending, or so it seems.
My husband and I have two rambunctious boys. We both have a hard time believing Max's injuries happened the way that Rebecca claims they did. I'm not accusing her or anyone of anything. I just can't believe the child fell the way she claimed he did.