Sounds like you need to re-do the taping job. Sealant coming through the spokes pretty much guaranties this is going to not hold air for long.

Regarding how tight the tires are: Is the tape fully seated (and sticking) into the center channel of the rim? The purpose of that channel is the allow the tire bead to drop down into to give you some slack while trying to get the last bit of the bead of the tire over the rim. It can be a PITA to stretch the tape tight enough to get it to go all the way down into the channel. If it is not fully down in the channel, then the tire bead can't go down into that channel, and the tire will be a lot harder to mount.

Another question is how wide is the tape and what is the internal width of the rim?