According to SVG spec, alignment-baseline only applies to <tspan>, <textPath>, <tref> and <altGlyph>. My understanding is that it is used to offset those from the <text> object above them. I think what you are looking for is dominant-baseline.
Possible values of dominant-baseline are:
auto | use-script | no-change | reset-size | ideographic | alphabetic | hanging | mathematical | central | middle | text-after-edge | text-before-edge | inherit
Check the W3C recommendation for the dominant-baseline property for more information about each possible value.